Refurbing a Very Early A/C System

[DMC-81]

Hi there,

I am in the process of refurbishing my "very early" A/C system, and I thought I'd document my adventure and what I learned in this thread.

The current state of my system is:

- Completely original
- The OEM Sankyo SD510 compressor engages when manually tripped
- The refrigerant is R12
- The system seems tight and is holding refrigerant, but the amount is unknown

At one point, it cooled briefly, but then stopped cooling and the compressor is not building pressure. After some troubleshooting, I suspect a blockage, but it could also be a compressor failure. I have a primary plan and back up plan to get the system operating again.

My Primary goal is to:
Refurbish my original compressor
Maintain the early style accumulator configuration
Keep the system on R12
Add the high pressure switch and pressure release valve that is missing on my system

And if that doesn't work out, my back up plan is to:
Replace the compressor
Convert to the later style accumulator
Convert to R134a

Here are some pictures:

Compressor:
53233

Early Accumulator 100743, without the cross on the crossover hose:
53234

Lower condenser hose without the later condenser adapter:
53235

My first step is to pull vacuum on the system before dismantling it to double check for a small leak...

[David T]

Best advice would be to go to an A/C shop and have them check it out.

[DMC-81]

Best advice would be to go to an A/C shop and have them check it out.

Thanks. I got advice from a few shops and the consensus is that the system needs a repair/rebuild.

---------------------------------------

Yesterday morning I attached my gauges and a pump and vacuumed down the empty system. It achieved 60hg quite quickly. I read in a few places to go down to 20-30 so I didn't want to go any further. So I closed the low pressure valve and shut off the pump.

53243

Initial reading:
53244

I checked the gauges every hour or so and up to 12 hours later, it was still on 60hg. 24 hours later, the reading was 55 -57 hg:
53245

What do you all think? Is this defined as a tight system, or do I have a very slow leak? I suppose the fact that it had gauges attached could introduce leak points. The car was not registered for 14 years before I got it yet it still had refrigerant in the system.

[Bitsyncmaster]

It seems pretty good. Using vacuum is not a perfect test but a good ball park. It's best to change the service valves anyway since those tend to leak with age. You want to pull a good vacuum when your ready to charge. Best to run the vacuum pump for at lease one hour. Then purge the fill hose running a little refrigerant through the open hose end.

[DMC-81]

It seems pretty good. Using vacuum is not a perfect test but a good ball park. It's best to change the service valves anyway since those tend to leak with age. You want to pull a good vacuum when your ready to charge. Best to run the vacuum pump for at lease one hour. Then purge the fill hose running a little refrigerant through the open hose end.

Great. Thanks Dave.

[David T]

Hard to really test for leaks with vacuum. Since atmosphere is 15 psi the most you can go is negative 15 psi or 30" of vacuum. And all you can tell is if it leaks or not, you cannot find a leak that way. A good shop will pressurize the system to 100 psi with Nitrogen and then use a leaktest solution (soapy water and Glycerine) and spray it at the joints to check for bubbles (leaks). Since you are trying to "do it on the cheap" drain the oil out of the compressor and refill with fresh. Change the valve cores. Pressurize with dry shop air to 100 psi and check for leaks at every joint. Fix any leaks and evacuate again for at least 1 hour and then refill with R-12. The longer the vacuum the better, you are trying to evaporate (boil) any moisture out that is in the system, not just suck out all of the air. It takes some time. To speed it up you can use a heat gun on the accumulator to dry out the desiccant. If the hoses are original you really should replace them and the accumulator.

[DMC-81]

Hard to really test for leaks with vacuum. Since atmosphere is 15 psi the most you can go is negative 15 psi or 30" of vacuum. And all you can tell is if it leaks or not, you cannot find a leak that way. A good shop will pressurize the system to 100 psi with Nitrogen and then use a leaktest solution (soapy water and Glycerine) and spray it at the joints to check for bubbles (leaks). Since you are trying to "do it on the cheap" drain the oil out of the compressor and refill with fresh. Change the valve cores. Pressurize with dry shop air to 100 psi and check for leaks at every joint. Fix any leaks and evacuate again for at least 1 hour and then refill with R-12. The longer the vacuum the better, you are trying to evaporate (boil) any moisture out that is in the system, not just suck out all of the air. It takes some time. To speed it up you can use a heat gun on the accumulator to dry out the desiccant. If the hoses are original you really should replace them and the accumulator.

Yeah, I was only attempting to confirm a tight system with this vacuum test as my baseline. I intend to have a qualified shop leak test it after I refurbish the system.

By the way, I'm not trying to "do it on the cheap". I don't know where you read that. I'm trying to preserve as much of the original configuration as possible as I refurbish the system. I suspect that's not going to be cheap.

[cdrusn]

I'm still not sure why you didn't just add Freon in the beginning to achieve proper pressure. You said you didn't know how much Freon you had in the system so you don't know if the a/c wasn't cooling due to lack of Freon. Was your compressor running with the clutch engaged?
Unless you want to just dump money into it, I would go ahead and convert to R134. Dump the old compressor oil and refill with 8 ounces of PAG oil. Get the conversion valves, take out the old R12 cores, screw on the new valves and fill the system with a can with dye in it and a plain can without it running. That will let you know if it is leaking. If it holds to 35 psi on the low side, start the a/c up and see if the clutch kicks in and you have a/c.
I think you are trying to make a reason for buying a whole new system and you may not need to. It might work just fine. What ever you do stay away from the "professional" a/c guys they always want to replace major components. Trouble shoot it your self and then you can go to the "professionals" with some knowledge of what has to be done. As much as a/c guys like to make it seem like black magic, it is just another system to trace out and fix. :race:

[David T]

Yeah, I was only attempting to confirm a tight system with this vacuum test as my baseline. I intend to have a qualified shop leak test it after I refurbish the system.

By the way, I'm not trying to "do it on the cheap". I don't know where you read that. I'm trying to preserve as much of the original configuration as possible as I refurbish the system. I suspect that's not going to be cheap.


I guess I thought that because you are trying to work on it yourself. I see no problem in trying to keep it original but I would try to replace the hoses. If you look hard enough you should be able to do that and have them still look original. Places like Classic Air in Florida makes up custom sets of hoses to duplicate any look you want using modern materials. Send them your old ones and they can duplicate them. Have your shop change the oil in the compressor. I do not like leak testing with vacuum, you just draw in air and contaminants through the leaks.

[DMC-81]

I'm still not sure why you didn't just add Freon in the beginning to achieve proper pressure. You said you didn't know how much Freon you had in the system so you don't know if the a/c wasn't cooling due to lack of Freon. Was your compressor running with the clutch engaged?
Unless you want to just dump money into it, I would go ahead and convert to R134. Dump the old compressor oil and refill with 8 ounces of PAG oil. Get the conversion valves, take out the old R12 cores, screw on the new valves and fill the system with a can with dye in it and a plain can without it running. That will let you know if it is leaking. If it holds to 35 psi on the low side, start the a/c up and see if the clutch kicks in and you have a/c.
I think you are trying to make a reason for buying a whole new system and you may not need to. It might work just fine. What ever you do stay away from the "professional" a/c guys they always want to replace major components. Trouble shoot it your self and then you can go to the "professionals" with some knowledge of what has to be done. As much as a/c guys like to make it seem like black magic, it is just another system to trace out and fix. :race:

Good points. Thanks! I was able to determine that despite normal readings, and the compressor engaging normally, the system wouldn't build pressure... even after ruling out a failed low pressure switch. My A/C shop said that it was either a blockage or a failed compressor.

Either way, it needs repair/refurbishment, and then I'll have it properly charged to spec. :wrenchin:


I guess I thought that because you are trying to work on it yourself. I see no problem in trying to keep it original but I would try to replace the hoses. If you look hard enough you should be able to do that and have them still look original. Places like Classic Air in Florida makes up custom sets of hoses to duplicate any look you want using modern materials. Send them your old ones and they can duplicate them. Have your shop change the oil in the compressor. I do not like leak testing with vacuum, you just draw in air and contaminants through the leaks.

That's fair enough. I work on my own car because that's what I bought it for. It's mechanical therapy for me. I've been planning this job off and on for a year, talking to people, learning, and gathering parts. For hoses, I know of at least 5 companies in Florida that can make them. I definitely want one piece hoses, so if I replace them I'll have choices.
I've already contacted a similar company to the one you named and I think I'll have them do some work on a different part.

------------------------------

Well, I was able to remove the orifice tube today. I used an orifice tool from a rented OEM A/C kit. The tool hooks on the the end of the tube so you can pull it out.

Here's the tool with a new tube:
53278

Here is how far it was in the pipe:
53281

Here is my old tube. I clipped on to it with the tool and pulled gently. It came out with no problems and aside from a little bit of debris, it was not clogged or had any ominous signs. Whew!
53280

[cdrusn]

Now you know it's the compressor. Easy to swap out. If you must change the hoses now's the time. If the hoses look o.k. I would take the chance and put the compressor in and fill it up. R134 is $6 a can at Walmart. You can test the old compressor by taking off the hoses and plugging the suction and discharge holes with your finger. Hold in the clutch and rotate, you can feel the sucking and blowing if it's working. :race:

[BABIS]

Well, I was able to remove the orifice tube today. I used an orifice tool from a rented OEM A/C kit. The tool hooks on the the end of the tube so you can pull it out.

Here's the tool with a new tube:
53278


this tool looks ace!

[DMC-81]

this tool looks ace!

Indeed! It made the job a breeze. Here is a picture of the separate orifice tool from the one in the whole A/C kit:

OEM #27003 for GM, or OEM #27004 for GM and Ford

53289

Here is a close up of the whole A/C kit, OEM #27150:

53290

[DMC-81]

I removed my compressor next and tore it down to assess the condition and if it is still good, replace the shaft seal, etc.

Compressor disconnected and ready to be removed. First was removing the 3/8" bolt holding the hose bracket, Then, there were 6 M10 nuts and washers (locking and flat) that hold the compressor to the bracket. I removed the 3 back bolts and slid the compressor forward (towards the rear of the car) as I couldn't remove the other 3 because the pulley was in the way:
53305

I rented a clutch holding tool, but the hole in the center was too small to fit the 19mm socket. So, I just used my air ratchet just a bit to break it free. That worked no problem:
53306

I borrowed the Deluxe A/C clutch hub puller and installer kit posted above from Auto Zone to remove the armature plate:
53307

Armature plate removed. You remove this snap ring to remove the pulley hub. The snap ring has a beveled and a flat side. The beveled side goes up:
53308

There were 2 shims on the shaft and a woodruff key that I removed:
53309

I rented this OEM #27078 jaw puller to remove the pulley assembly:
53310

I sprayed a little bit of WD-40 where the the inner race of the bearing meets the shaft hub. Then I positioned the puller and the pulley came off easy after a little bit of initial resistance:
53311 53312

Next, I removed the snap ring for the coil and the Phillips screw and bracket that holds the wire. Then the coil came off easily. Same thing as before: the snap ring has a beveled and a flat side. The beveled side goes up.
53313

To be continued...

[DMC-81]

Disassembly continued..

My next step was to remove the 8 M6 bolts and using a rubber mallet I gently tapped the cover loose. There was minimal oil in the compressor, yet it was good to see that there was no damage or debris:
53347

Here's a close up of the 5 cylinder walls and the reed valves, both looking pretty good:
53348

Here's a close up of the swashplate assembly. The pistons don't exhibit any scoring that I can see:
53349

It looks like this compressor is still good. Therefore, I'll clean it well, and put it back together with new seals and a little bit of mineral oil on the moving parts during reassembly. (I will stay with mineral oil in the system.)

[DMC-81]

Today I got some work done on my compressor.

Cylinder Head cover cleaned:
53594

After removing the 5 bolts I used a rubber mallet to knock the cover loose from the seal:
53595

On closer inspection, the reed valves still look good. I'll replace the seals:
53596

2 sets of thrust bearings cleaned with mineral spirits and lubed with mineral oil:
53597

..and the inside of the front cover:
53598

..plus the piston assembly:
53599

After cleaning the main case, the spring, and the woodruff key, the piston assembly is ready to go back together:
53600

Back together in the same orientation, lubing with mineral oil:
53601

[David T]

A LOT of work. It is often a better choice to just get another compressor, they aren't expensive or hard to find. I hope when you are all done it works OK and doesn't leak.

[NckT]

Good work there Dana, keep it up :)

I'd recommend to soak any O rings in air con mineral oil overnight before fitting to aid sealing.

[DMC5180]

The puzzler here is that it didn't build system pressure. Because it is closed loop, any blockage/restriction should cause the Highside to climb like crazy.

Broken reed valves would cause no pressure to build. But from your teardown inspection all the components appear to be good.

Fwiw, when you reassemble the clutch, be sure the air gap is within spec.
.016"-.031". Adjust or remove shims as needed to bring into spec. When I was redoing my system last year, I noticed the clutch was slipping intermittently. The Clutch Air gap was almost .060. Since I was replacing the compressor anyway with an SD7H15, it didn't matter to me. For comparison the New compressor's clutch was near the bottom of the spec.

[David T]

You can tell if the compressor is turning by observing the clutch. I worked on one car, the clutch would engage fine but once it let go, it could not re-engage the clutch again. Checked the gap and it was way too big. Removed some shims and it was fine. Yes, if it is turning you should see some pressure differential between the high and low sides if it is working. When you don't see any action you check the oil for metal and when you tear it down you should have found *something* not right. Are you sure your test lines depressed the service valves and your manifold gauge works? When I do something and doesn't seem to make sense I recheck what I did to make sure I didn't do anything wrong.

[DMC5180]

Are you sure your test lines depressed the service valves and your manifold gauge works? When I do something and doesn't seem to make sense I recheck what I did to make sure I didn't do anything wrong.

Back in post #3 it says the vacuum pulled down to 60hg quite quickly.

Btw, thats a cmHg scale. Normally it would be INHg
30-31 inhg would be normal full vacuum.

Which makes me think that the gauge valves might not be open.

[DMC-81]

Good work there Dana, keep it up :)

I'd recommend to soak any O rings in air con mineral oil overnight before fitting to aid sealing.

Thanks! I'll do that.


The puzzler here is that it didn't build system pressure. Because it is closed loop, any blockage/restriction should cause the Highside to climb like crazy.

Broken reed valves would cause no pressure to build. But from your teardown inspection all the components appear to be good.

Fwiw, when you reassemble the clutch, be sure the air gap is within spec.
.016"-.031". Adjust or remove shims as needed to bring into spec. When I was redoing my system last year, I noticed the clutch was slipping intermittently. The Clutch Air gap was almost .060. Since I was replacing the compressor anyway with an SD7H15, it didn't matter to me. For comparison the New compressor's clutch was near the bottom of the spec.

Yeah, I expected a failed compressor or a plugged orfice tube, but I have yet to check the evaporator and condenser. Thanks for the air gap specs, I'll be sure to check it during assembly. I checked that during evaluation before disassembly and it was within spec.



Back in post #3 it says the vacuum pulled down to 60hg quite quickly.

Btw, thats a cmHg scale. Normally it would be INHg
30-31 inhg would be normal full vacuum.

Which makes me think that the gauge valves might not be open.

Correct, but I tested the system 3 times before teardown and the high side gauge:
- needed to be purged
- showed readings all 3 times (and some mild fluctuations)
- and went negative during vacuuming.
If either side was not connected, I would expect a zero reading, right?

Good discussion.

Regardless, I'm in the refurbishment process now, which I needed to do anyway to replace the seals, orifice tube and accumulator. :wrenchin:

[DMC5180]

In case you didn't know this was an available resource.

Sanden SD AC Compressor Service Manual

https://r.tapatalk.com/shareLink?share_fid=24478&share_tid=353&url=http%3A%2F%2Fdmctalk%2Eorg%2Fshowthread%2Ephp% 3Ft%3D353&share_type=t

[David T]

If you didn't depress the service valves and tried to pull a vacuum you would see a negative reading on your gauges. It would be the vacuum in the hoses right up to the service valves. You might think you have a vacuum going into the system but it only goes up the the cores of the service valves. It is possible the clip that depresses the cores is missing OR you put the hoses on the manifold on backwards and the clips are on the manifold side. One reason when I pull a vacuum I like to use a core extractor. That way I KNOW I am into the system and I have a much larger passageway into the system.

[DMC-81]

If you didn't depress the service valves and tried to pull a vacuum you would see a negative reading on your gauges. It would be the vacuum in the hoses right up to the service valves. You might think you have a vacuum going into the system but it only goes up the the cores of the service valves. It is possible the clip that depresses the cores is missing OR you put the hoses on the manifold on backwards and the clips are on the manifold side. One reason when I pull a vacuum I like to use a core extractor. That way I KNOW I am into the system and I have a much larger passageway into the system.

Good information. Makes sense. Although in my case, I'm pretty sure I pulled the vacuum right. I used new (tested) gauges that were demonstrated as being effective at depressing the service valves.

[DMC-81]

While waiting for a special tool for the compressor, I was finally able to remove the A/C Accumulator yesterday. I struggled to crack the evaporator to accumulator connection loose, mainly due to space and the angle. I have heard that you can access this fitting via the fuel tank access panel, however, for me, I found the heater and fuel hoses in the way. So this is the position that I was best able to reach it. After trying a special 1 1/16" crow's foot and angled combination wrench, the tool that accomplished the task was an adjustable wrench. Who knew!! I removed the bracket ring first but snugged up the bottom fitting again (which I had already loosened) to keep things as rigid as possible.

53658

I was very cautious to avoid bending the soft aluminum evaporator tubes. I used the the other 2 tools to gently work the #12 male o-ring fitting back. I also put the liquid line back on to help keep that evaporator tube as steady as possible.

53659

Success! Here are the tools that I used. 1 1/16" is the proper size wrench on the evaporator end and 1 1/4" on the accumulator side. Same sizes for the bottom tube to #12 suction hose. Although, I found that I didn't need the 1 1/4" wrench on the top fitting as I held the accumulator steady with my hand.

53660

I packaged it up and sent it away to Original Air in Tampa today for rebuilding. Fingers crossed!

53661

[DMC-81]

Today, I cleaned the small portion of the frame behind the accumulator.

Before:
http://dmctalk.org/attachment.php?attachmentid=53727&d=1506820466

After:
http://dmctalk.org/attachment.php?attachmentid=53728&d=1506820629

Early cars up to a certain VIN don't have a high pressure switch (or safety release valve), so, as part of my refurbishment of this system, I'm going to add them. First to be installed is the DMC high pressure switch wiring harness (110526). One end needs to go through the hole in the firewall. First, I threaded some spare wire that I had through the hole from the inside. Then I taped it to the harness. I put plastic around the connector to protect it from the the gooey cork tape.
http://dmctalk.org/attachment.php?attachmentid=53729&d=1506820744

I found that it was too tight to squeeze between the biggest space between the 2 evaporator tubes. Because the molex connector was the thing that got caught up, I carefully removed it and taped the harness to the spare wire that I had, then taped it up:
http://dmctalk.org/attachment.php?attachmentid=53730&d=1506821355

On this second attempt, it threaded through easily. Notice the connector with the jumper attached. This is where it connects on later cars. On my early car, the provision was there in the main harness, but it wasn't used.
http://dmctalk.org/attachment.php?attachmentid=53732&d=1506821795

After reinstalling the connector, I removed the factory jumper and plugged the harness in, threaded the extra harness back through to the outside, then zip tied it out of the way:
http://dmctalk.org/attachment.php?attachmentid=53734&d=1506822043

Now I have both low and high pressure connectors ready to go:

http://dmctalk.org/attachment.php?attachmentid=53735&d=1506822290

[DMC5180]

That is what I had to do when I replaced my Relocated my HP switch to the Outlet adapter on the lower condenser connection.

Btw, is that HP switch harness about 4 ft long? If so, it is intended to reach the HP switch at the condenser. The early version that used the Hub hose assembly that had the switch a few inches away from the accumulator was a much shorter harness.

[DMC-81]

That is what I had to do when I replaced my Relocated my HP switch to the Outlet adapter on the lower condenser connection.

Btw, is that HP switch harness about 4 ft long? If so, it is intended to reach the HP switch at the condenser. The early version that used the Hub hose assembly that had the switch a few inches away from the accumulator was a much shorter harness.

Cool, and thanks for letting me know about those 4 parts. Yes, this harness is about 4 feet long. I trial fitted it and it is long enough to follow the condenser/evaporator line (110525) and connect to the hub/adapter (110527).

[NckT]

Great work, I'm enjoying reading this overhaul.

May I suggest that as soon as you connect the accumulator, as it also contains the drier silica gel, immediately pull a vacuum in to prevent the gel from absorbing moisture from the atmosphere/ moisture present by air in the refrigerant pipes.

Good luck with the project :)

[DMC-81]

Great work, I'm enjoying reading this overhaul.

May I suggest that as soon as you connect the accumulator, as it also contains the drier silica gel, immediately pull a vacuum in to prevent the gel from absorbing moisture from the atmosphere/ moisture present by air in the refrigerant pipes.

Good luck with the project :)

Thanks! That is a great tip. I'll definitely do that.

[DMC-81]

Today, I began by cleaning the compressor brackets. I also blasted compressed air through the high pressure hose & condenser, and through the evaporator. The air passed through just fine. That was good news, as it indicates the entire system is free of any blockages.

http://dmctalk.org/attachment.php?attachmentid=53773&d=1506899088

Next, I began replacing the front seal (Santech MT2043 kit). It was highly recommended to use a special seal protector (Santech MT4024) to stretch the seal and protect it from being damaged by the threaded portion on the shaft when you install the front cover. The parts of the seal came out of the housing in the order pictured, first the felt ring, then the snap ring and the metal retainer/washer, then the O-ring and finally the carbon seal assembly. Once the snap ring was removed, I just tapped the retainer/washer out from the inside using a medium nail punch. It is only restricted from coming out by the tension on the O-ring, so it just needed a firm tap.
http://dmctalk.org/attachment.php?attachmentid=53774&d=1506899596

New seal parts laid out in order. Before I began installing it, I cleaned the bore area with an old toothbrush and mineral spirits, then blasted it with compressed air to make sure there was no debris:
http://dmctalk.org/attachment.php?attachmentid=53776&d=1506900376

Next, the carbon seal assembly went in with the metal end to the inside, then the green HNBR O-ring which was soaked in mineral oil. Then I applied extra oil to the O-ring and the bore using a clean artist's brush:
http://dmctalk.org/attachment.php?attachmentid=53777&d=1506900881

Next came the metal retainer/washer. I just lubed the edges with oil, then pushed it in place evenly using both thumbs. Then came the snap ring, beveled side up:
http://dmctalk.org/attachment.php?attachmentid=53778&d=1506901272

Finally, the felt ring is pressed into place. This seal package didn't come with a new one, so I soaked my old one in mineral spirits to clean it, let it dry for a couple days, and then re-used it. It came out just like new.
http://dmctalk.org/attachment.php?attachmentid=53779&d=1506901557

[DMC-81]

Well, it was time to re-install the Front Head Plate on the compressor. In this picture, I had the parts laid out to do the task: a seal kit from Santech ( MT2143 ), and the seal protector sleeve. Besides the large square cut head plate O-ring, the kit also contains the two gaskets for the rear cover/cylinder head, and a green HNBR O-ring for the oil fill plug.
http://dmctalk.org/attachment.php?attachmentid=53802&d=1507074014

Seal protector sleeve in place (and lubed) on the shaft, and the two sets of thrust bearings on both sides of the driver assembly, lubed with mineral oil and aligned:
http://dmctalk.org/attachment.php?attachmentid=53803&d=1507074577

New head plate O-ring in place with a little bit of mineral oil around it to prevent it from jumping out of its groove:
http://dmctalk.org/attachment.php?attachmentid=53804&d=1507075490

I carefully lowered the front seal through the seal protector, and aligned/positioned the front head plate and driver assembly. It is under a little bit of spring tension, so I started 4 bolts in each cornering, gently tightened them equally to draw the plate until it seated, making sure it didn't bind. Then I inserted and tightened all bolts similar to a head sequence. Then I torqued them to 23 inch pounds.
finally, I trial fitted the armature assembly so I could rotate the shaft to ensure free movement. It worked nice and smoothly.
http://dmctalk.org/attachment.php?attachmentid=53805&d=1507075692

[David T]

Since you are going through all of this trouble and the system is "open", before you put it all back together and close it up, the last thing you should do is run flush through the condenser and evaporator cores. That will remove any residue, old oil, and most moisture. Kind of getting the insides back to like new condition. Don't run the flush through the accumulator or the compressor. Hook them up last. Then immediately fill with Nitrogen to pressurize the system with dry gas so you can pressure test for leaks.

[DMC-81]

Since you are going through all of this trouble and the system is "open", before you put it all back together and close it up, the last thing you should do is run flush through the condenser and evaporator cores. That will remove any residue, old oil, and most moisture. Kind of getting the insides back to like new condition. Don't run the flush through the accumulator or the compressor. Hook them up last. Then immediately fill with Nitrogen to pressurize the system with dry gas so you can pressure test for leaks.

Thanks. Yes definitely, flushing is coming up soon. There was no oil in the compressor, so there's approximately 6 oz of old oil elsewhere that needs to be flushed. I checked on the accumulator today, and Original Air should be done rebuilding it by the 10th. It should arrive sealed and good as new. So definitely, I won't run flush through it.

Now, your advice to immediately fill with Nitrogen is contrary to what NickT said about immediately vacuuming it down to remove moist air.

So, should I do one and not the other, or both. If both, which one is first? I'm thinking an intitial vacuuming to remove moisture (while checking the gauges for any major leaks), and then pressurize with nitrogen to test for leaks. Then a final vacuum before recharge.

[Bitsyncmaster]

Dry Nitrogen would be fine to keep the unit dry until you recharge it. But it's mostly just used for pressure testing. Not many of us keep a tank of nitrogen around.

[David T]

It's a judgement call about the order. If yo have a big leak and you try to vacuum the system you are only drawing in more air and moisture. If it is cool and dry when you do it, it isn't a big deal. If you have clean, dry shop air you can pressure it to about 100 psi but an A/C shop (a GOOD shop) will have a bottle of Nitrogen and pressure test at 200 psi. Not uncommon. Good shops have the right tools and know how to use them. Just saying how it should be done, Different shops use different procedures (read short-cuts).

[DMC-81]

I refurbished the rear cover this weekend. Here is the head gasket removal in progress. I soaked the old fiber gasket in mineral spirits for a week, and then carefully scraped it off using a razor blade, and a dull putty knife, being very careful not to bend the reed valves. I angled the blades at a steep angle to avoid scratching the valve plate surface. I also used Goo Gone after the gasket was torn which dissolved it well.
http://dmctalk.org/attachment.php?attachmentid=53864&d=1507415835

Interior gasket removed:
http://dmctalk.org/attachment.php?attachmentid=53865&d=1507416271

Here is the outer gasket separated from the rear cover. I gently pried the plate off the cover:
http://dmctalk.org/attachment.php?attachmentid=53866&d=1507416617

To completely remove the gasket material from the valve plate, I first dissembled the valves and removed the 2 guide/roll pins, and then sprayed it liberally with Goo Gone and let it sit for a few minutes. Then I scraped it gently with a razor blade, then wet sanded it with 600 grit (with a block) and Goo Gone, followed by wet sanding with 1000 grit and mineral spirits:
http://dmctalk.org/attachment.php?attachmentid=53893&d=1507497146

Both sides of the valve plate clean and smooth, ready for re-assembling the valve assembly:
http://dmctalk.org/attachment.php?attachmentid=53894&d=1507497890

I reinstalled the guide pins, coated each part in mineral oil, aligned the valves on both sides, then hand tightened the nut:
http://dmctalk.org/attachment.php?attachmentid=53895&d=1507498058

Then I torqued the M6 nut to 36 inch pounds:
http://dmctalk.org/attachment.php?attachmentid=53896&d=1507498890

I used the same process described above to remove the gasket on the rear cover, this time using a longer blade across both sealing surfaces to maintain the flat surface of the thin aluminum material:
http://dmctalk.org/attachment.php?attachmentid=53897&d=1507498993

Rear cover clean. Here are the gasket kits, rear kit (Santech MT 2143) and a general HBNR O-ring kit (Santech MT 2547) or the DMC O-rings for the rear cover 100747:
http://dmctalk.org/attachment.php?attachmentid=53898&d=1507499282

Interior metal gasket coated with oil on both sides and placed:
http://dmctalk.org/attachment.php?attachmentid=53899&d=1507499888

Valve plate placed. I was careful with the orientation:
http://dmctalk.org/attachment.php?attachmentid=53900&d=1507500097

Outside metal gasket placed with oil on both sides:
http://dmctalk.org/attachment.php?attachmentid=53901&d=1507500215

Rear cover placed, and the M8 bolts hand tight:
http://dmctalk.org/attachment.php?attachmentid=53902&d=1507500357

Then, the five M8 bolts were progressively torqued to 26 ft/lbs and the ports temporarily blocked off:
http://dmctalk.org/attachment.php?attachmentid=53905&d=1507500726

Compressor rebuilt. I discovered that it was painted with an aluminum colored paint so I'll refresh that before reinstalling the clutch, pulley, and armature....:
http://dmctalk.org/attachment.php?attachmentid=53906&d=1507500854

:wrenchin:

[NckT]

Excellent :)

[DMC-81]

Just an update: To prep for painting, I wet sanded the compressor with 600 grit, cleaned and masked it. I also increased the torque for the 5 head bolts to from 26 to 29 ft/lbs:
http://dmctalk.org/attachment.php?attachmentid=53920&d=1507676259

Here is the compressor after spraying with 3 coats of VHT aluminum caliper paint:
http://dmctalk.org/attachment.php?attachmentid=53922&d=1507676494

I cleaned up the coil and the armature plate, and wrapped the coil wire around a screwdriver shaft to simulate the original winding:
http://dmctalk.org/attachment.php?attachmentid=53928&d=1507678056

----------------------

Excellent :)

Thanks!! :)

[DMC-81]

While waiting for the compressor paint to cure, I assembled the pressure release valve (106918 ) and the high pressure switch (106917) onto the hub adapter (110527):
http://dmctalk.org/attachment.php?attachmentid=53923&d=1507676749

I began removing 30 years of oxidation off the hub adapter using Mother's Mag & Aluminum polish, (or maybe it was raw aluminum anyway). I also replaced the Schrader valve in the high pressure switch fitting with a new one featuring neoprene seals. I think DMC already replaced it as the old one was the same as my new one. I used this "Slime" valve core tool (#20178 ) that clicks/releases when the valve is sufficiently tight:
http://dmctalk.org/attachment.php?attachmentid=53924&d=1507677097

I also replaced the 3 O-rings with HNBR versions that I got from the same kit listed in an earlier post, soaking them in mineral oil first and using oil on the threads:
http://dmctalk.org/attachment.php?attachmentid=53925&d=1507677670

Both switches tightened, and the polishing done. I used two small applications of the polish and just a bit of rubbing it in and off with a shop paper towel and it turned out better than I expected. Also, I think I'll find a suitable rubber plug for the hole in the top of the pressure release valve to keep water out of it:
http://dmctalk.org/attachment.php?attachmentid=53927&d=1507677961

Other than that, this is ready to go on the car.

[DMC-81]

I found this little nylon beauty plug locally at Ace Hardware to cover the hole in the top of the pressure release valve. That should stop water and dirt without impeding the function:
http://dmctalk.org/attachment.php?attachmentid=54100&d=1508031565

The compressor paint is sufficiently cured, so I reassembled the front portion, clutch coil first. As before, the beveled side of the snap ring faces you:
http://dmctalk.org/attachment.php?attachmentid=54095&d=1508029653

Pulley installed. I put some oil around the inside of the bearing race and tapped it in place using a rubber hammer. Then the snap ring:
http://dmctalk.org/attachment.php?attachmentid=54096&d=1508029888

Next, I installed the 2 shims and then positioned the armature plate in place after putting a little bit of oil around where it presses onto the shaft. I used a 19 mm socket in the center and tapped it in place using a rubber hammer.
http://dmctalk.org/attachment.php?attachmentid=54097&d=1508030160

I used OEM A/C Clutch Holding Tool ( part # 27000) and a 19mm socket to torque the armature nut to 25.5 ft/lbs. Then I checked the air gap. As Dennis mentioned earlier the spec is .016" to .031" . Mine was .025" :
http://dmctalk.org/attachment.php?attachmentid=54098&d=1508030850

Compressor ready to be re-installed:
http://dmctalk.org/attachment.php?attachmentid=54107&d=1508038656

[DMC5180]

Dana,

It seems like you skipped over the part of piston and swash plate reassembly. Did you replace the Rings? I assume the pistons and cylinder bores showed no signs of wear.

[DMC-81]

Dana,

It seems like you skipped over the part of piston and swash plate reassembly.

Hi Dennis,

Sorry, here is the piston & swashplate assembly ready to go back together. I re-assembled it by orienting the pinion and ball bearing with the 5 pistons closed in around it, then positioning the woodruff key and spring in the case, then carefully lowering the piston/swashplate assembly down in the case. It took half a dozen tries to get it seated so I could then position each piston in the cylinders. I lubed each part with mineral oil, applied by a clean artists brush:
http://dmctalk.org/attachment.php?attachmentid=53592&d=1506217434

Here is the assembly installed in the original orientation:
http://dmctalk.org/attachment.php?attachmentid=53593&d=1506217536


Did you replace the Rings? I assume the pistons and cylinder bores showed no signs of wear.

Although Sanden says the piston assembly cannot be refurbished ( i.e. rings, etc), you are correct that there was no scoring in either the bores or the pistons or any sign of wear. After the compressor was put back together, I turned the armature slowly by hand and I could feel a slight suction. I don't know how fast it has to move for there to be real suction for a test.

[DMC5180]

Thanks for the added info.

At some point this thread needs to be placed in the How To Section. Great detail write ups and photo documenting. Granted most folks would not go through the tear down like you have but still great stuff. It also takes a lot of the mystery out of what’s inside a typical A/C compressor.

[DMC-81]

Thanks for the added info.

At some point this thread needs to be placed in the How To Section. Great detail write ups and photo documenting. Granted most folks would not go through the tear down like you have but still great stuff. It also takes a lot of the mystery out of what’s inside a typical A/C compressor.

You're welcome, and thanks for the compliment. I hope that it is useful to anyone reading it.

My next post will be flushing.

[DMC-81]

Next, it was time to flush the A/C system to remove old oil and any debris. I used this OEM Automotive A/C Flushing Kit (part # 91046-A-AZ ). It worked beautifully! Just pour in 32 oz of mineral spirits, connect to your air compressor, and hold the nozzle tight against the hose/part you are flushing.
http://dmctalk.org/attachment.php?attachmentid=54109&d=1508101637

Here is the set-up I used to control the flushing output. A short length of appropriately sized hose and a bucket.
http://dmctalk.org/attachment.php?attachmentid=54110&d=1508102109

After I arranged the hose and bucket, I covered it with some heavy plastic sheeting to help control the mist/splash.
http://dmctalk.org/attachment.php?attachmentid=54111&d=1508102473

I covered the hoses at the compressor end with some old heavy bath towels to protect the area from blowback. Then I used the Flushing Kit on these ends of the hoses. I flushed the low pressure line, the high pressure line & condenser, the liquid line, and finally the evaporator separately (with 32 oz of mineral spirits per section).
http://dmctalk.org/attachment.php?attachmentid=54112&d=1508102734

Here is the mineral spirits after the flushing. It seemed that most of the old oil was in the evaporator. I researched it and it seems my blockage was too much oil in the evaporator, and the condition is called "oil logged". It took extra effort to clean it all out.
http://dmctalk.org/attachment.php?attachmentid=54113&d=1508103917

Now the system is clean. I'll connect all the hoses possible and put the A/C Hub Adapter on next.

[DMC-81]

The next task was to connect all the hoses, finish the compressor, and connect the new AC Hub Adapter.

First, I replaced the O-rings for the pad fitting with ones from the same HNBR O-ring assortment (Santech MT 2547). This kit had all O-Rings that didn't come in the compressor gasket kits.
http://dmctalk.org/attachment.php?attachmentid=54122&d=1508201518


Then connecting the GM pad fittingsto the back of the compressor. I applied a little bit of anti-seize to the 3/8”-24 Pad Fitting bolt and progressively torqued it to 29 ft/lbs:
http://dmctalk.org/attachment.php?attachmentid=54127&d=1508202235

Next, I replaced the service valves with neoprene versions using the Slime valve core tool. I also polished the brass caps with Mother's Mag & Aluminum polish:
http://dmctalk.org/attachment.php?attachmentid=54128&d=1508202541

I added 8 oz of mineral oil to the compressor: 6 oz before installing it so I could rotate and tilt it to coat the full crankcase, and then 2 oz after it was installed:
http://dmctalk.org/attachment.php?attachmentid=54150&d=1508373913

I lubed the new HNBR O-Ring for the oil plug and torqued it to 15 ft/lb. The socket size was 17 mm:
http://dmctalk.org/attachment.php?attachmentid=54151&d=1508373984

I replaced and tightened the belt, and now the compressor ready for service:
http://dmctalk.org/attachment.php?attachmentid=54152&d=1508374057

Then, I replaced the O-Ring at the top fitting of the condenser. All O-rings were soaked in Mineral oil for at least overnight, plus I swabbed the threads with oil. I used a 1 and 1/16” angled service wrench to hold the condenser fitting stable and a 7/8” wrench for the high pressure hose:
http://dmctalk.org/attachment.php?attachmentid=54143&d=1508290028


Next was the A/C Hub Adapter. Adding this will solve a shortcoming of the Very Early A/C Setup. I used a 1 1/16” angled service wrench to hold the bottom condenser fitting stable, and a 3/4” wrench for the adapter nut:
http://dmctalk.org/attachment.php?attachmentid=54144&d=1508290467

Then the condenser to evaporator line. I was careful to position this line so that it has gentle rather than sharp curves:
http://dmctalk.org/attachment.php?attachmentid=54146&d=1508290933

When my accumulator arrives from Original Air, I'll connect that and install the Orifice tube.

[NckT]

Exciting times, you're almost there !

[DMC-81]

Exciting times, you're almost there !

Thanks! I got a lot done I the last 24 hours:

I got the accumulator so I proceeded to install the Orifice Tube/Valve. Here is the new fixed version (Santech MT 0097-1) compared to the old one. I used the same OEM Orifice tube tool to insert it. A long running A/C shop advised that a Variable Orifice Tube was not needed for R12, so I stuck with the original fixed version.
http://dmctalk.org/attachment.php?attachmentid=54153&d=1508374112

I clicked the tube in place and lubed its o-ring well before inserting it:
http://dmctalk.org/attachment.php?attachmentid=54154&d=1508374161

This is how far the tube was inserted. It just needed a gentle push to seat the o-ring:
http://dmctalk.org/attachment.php?attachmentid=54155&d=1508374257

Here is a picture of the orifice tube fully inserted:
http://dmctalk.org/attachment.php?attachmentid=54156&d=1508374315

My Accumulator arrived from being rebuilt by Original Air/Classic Air in Tampa. I am impressed at the quality of the work.
http://dmctalk.org/attachment.php?attachmentid=54169&d=1508472613

I replaced my Low Pressure/Cycling Switch with this exact replacement (Santech MT 0207):
http://dmctalk.org/attachment.php?attachmentid=54170&d=1508472815

New HNBR o-ring for the suction hose to accumulator, again from the same kit. The hose end uses a 1 and 1/4" wrench, and the lower fitting on the accumulator uses a 1 and 1/16" wrench:
http://dmctalk.org/attachment.php?attachmentid=54171&d=1508472991

...and, a new O-ring for the evaporator to accumulator, again lubing the threads. This nut uses a 1 and 1/16" wrench. I was able to just use my crow's foot wrench to tighten this one.
http://dmctalk.org/attachment.php?attachmentid=54172&d=1508473122

Accumulator installed. As NktT suggested, I connected a vacuum pump beforehand, and immediately started pumping the system down after the accumulator was connected. The liquid line to evaporator fitting used a 3/4" crow's foot on the evaporator end to hold it stable, and a 7/8" wrench on the hose nut. All these o-ring fittings didn't need a lot of torque.. just hand tight :
http://dmctalk.org/attachment.php?attachmentid=54173&d=1508473250

Next was installing the bracket and the 6mm bolt ( 10 mm tool) . I installed a new o-ring and lubed it and the threads, and gently tightened the plastic threads of the switch with a 5/8" wrench:
http://dmctalk.org/attachment.php?attachmentid=54176&d=1508474075

After connecting the harness, the early accumulator is refurbished and installed:
http://dmctalk.org/attachment.php?attachmentid=54177&d=1508474225

I vacuumed down the system overnight, and in the morning I shut off both red and blue valves and then turned off the pump. Here is the initial reading, 30 in/hg. After 4 hours, it maintained that reading:
http://dmctalk.org/attachment.php?attachmentid=54178&d=1508494503

I have an appointment this afternoon with an A/C shop to have it vacuumed again and then charged. Fingers crossed!!

[NckT]

That looks good to me. Good luck with the recharge. 975g of r134a have great results for me and others.

Don't forget to adjust the low pressure switch so that the compressor comes on at approx 44psi and off at approx 20psi. Run the engine at 1500rpm by applying 'bodge the throttle open with a screwdriver at the throttle stop' technique ;)

How much ester oil did you put in overall?

[DMC5180]

That looks good to me. Good luck with the recharge. 975g of r134a have great results for me and others.

Don't forget to adjust the low pressure switch so that the compressor comes on at approx 44psi and off at approx 20psi. Run the engine at 1500rpm by applying 'bodge the throttle open with a screwdriver at the throttle stop' technique ;)

How much ester oil did you put in overall?

He’s staying with R-12

[NckT]

I didn't realise you can still get ozone depleting refrigerant R-12 in America. It's banned elsewhere.

[ritztoys]

A few years after acquiring my car a local Car Dealer closed his business, I had the chance to go through the tools, before the Auction Co. came in to sell everything else.

I was lucky a Dial-A-Charge for $100 and it had 30lb of R-12 attached! I won't ever run out of this refrigerant.

My next charge, I'll flush my system. (a few years down the road)

[DMC-81]

Here are the Results:

Initial performance baseline before refurbishment. Cold engine at idle, ambient temperature 81 degrees, A/C on MAX with fan speed 3 => center vent temperature at 82 degrees (basically, no A/C):
http://dmctalk.org/attachment.php?attachmentid=53094&d=1503872683

Results after A/C system refurb and charge: Warm engine at idle, ambient temperature 80 degrees, A/C on "NORM" with fan speed 2=> center vent temperature at 48 Degrees:
http://dmctalk.org/attachment.php?attachmentid=54197&d=1508636967

:smile:

[DMC-81]

Just a one month update:

I replaced the tape around the A/C heater hose cover (105847), that I forgot to do at installation, and that made a difference in my vent temps. I read 42 degrees on the Bi-Level mode, fan speed 2 on my way home after the CFIAS show. Also, my system is still holding pressure. That's good news for a rebuilt compressor & accumulator and original hoses.

So far so good. :)

[dodint]

What an engaging read. Thanks for putting it all together and sharing.

[NckT]

Excellent well done

[DMC-81]

Thanks guys! It was an enjoyable exercise and I hope the thread is helpful.

[BABIS]

I replaced the tape around the A/C heater hose cover (105847), that I forgot to do at installation


I still have to replace that tape after my a/c box resto, but I don' t rembember if it was just around the pipes or around the whole #105847 seal, can you point me in the right direction? Thanks!

[DMC-81]

I still have to replace that tape after my a/c box resto, but I don' t rembember if it was just around the pipes or around the whole #105847 seal, can you point me in the right direction? Thanks!

Sure, for clarity, I was referring to the black duct tape that was around the outermost seal, not the gooey no-drip tape (106781) that was still present and in good shape on my car.

Originally there was only one piece basically on the top of the seal, but I cut pieces to fit in between the pipes as much as possible and followed that with tape around the circumference of the seal. Like so:

http://dmctalk.org/attachment.php?attachmentid=54777&d=1512233728

[Helirich]

Nice write up! For others that might be reading this, you can use argon for pressure test. It is dry like nitrogen and you might be more likely to have it around. (if you weld) It's more expensive, but you won't be using much.

[DMC-81]

Nice write up! For others that might be reading this, you can use argon for pressure test. It is dry like nitrogen and you might be more likely to have it around. (if you weld) It's more expensive, but you won't be using much.

Thanks!

[David T]

Any inert pressurized gas will do. Nitrogen is cheap and is what is used by A/C guys. In a pinch you can use dry pressurized air but the idea of Nitrogen is that because it is so highly pressurized, all the moisture is "squeezed" out of it.

[DMC-81]

By the way, I should give a status update:

At this time, which is 3 plus years since the refurb, this 40 year old system is still keeping the car cool. No top ups were necessary in the meantime.

[Helirich]

Any inert pressurized gas will do. Nitrogen is cheap and is what is used by A/C guys. In a pinch you can use dry pressurized air but the idea of Nitrogen is that because it is so highly pressurized, all the moisture is "squeezed" out of it.

Yea, I use to have a nitro bottle when I did refridge work. I was not in the business, but I got the license because I did so much refridge work on my wife's restaurant/bar. You can't believe how many units there are in one restaurant/bar.

It is the cheapest inert gas. I had a project where I needed to weld stainless tube. It's best to "back purge" tube with argon when welding on the outside. So I got the nitro bottle filled with argon and had a seperate line to the inside of the tube. After that job, I was welding a stainless fuel tank. Same thing applied about the back purge. Ever since, I've kept it charged with argon. It's nice to have a backup bottle for welding because argon always seems to run out right in the middle of a welding project.

[Henrik]

... the piston & swashplate assembly... Although Sanden says the piston assembly cannot be refurbished ( i.e. rings, etc)

As a former Sanden Compressor Application Engineer and Lab Manager...: Correct, the piston rings are non-replaceable. And to be really picky... the SD compressors use wobble plates, not swash plates. Awesome work Dana!

[DMC-81]

As a former Sanden Compressor Application Engineer and Lab Manager...: Correct, the piston rings are non-replaceable. And to be really picky... the SD compressors use wobble plates, not swash plates. Awesome work Dana!

Thanks Henrik!