General A/C Performance Question

[jawn101]

So this is more of a "I don't understand how something works" question than a specific problem, I guess.

I took my D out for the first time in a couple weeks today, it needed a wash to get the pollen off and I decided to cruise around to dry things and get some gas. No big deal. It's fairly cool here still - upper 50s. But, of course in the bright sun I started getting a little warm inside the car and turned on the A/C. It didn't really seem to be the arctic blast I was expecting.

Got home and did some testing. At idle, the compressor never seems to cycle off - just engages and stays. At about 2500-ish RPM, it engages on 7 seconds and off 4 seconds, which seems pretty reasonable.

The ambient air inside the car (IR thermometer pointed at the passenger seat) was about 64.8 degrees. Air from the center stack set to "Vent", full cold, Fan 4 was about 58. Put it to Max A/C instead and there wasn't really an appreciable difference at idle, but if I revved the engine to around 2500-3000 and the compressor started cycling, it would drop to the mid 40s.

All the electrical components seem OK. Engine fans kick on and off as they should, compressor cycles when there's some revs, fan speeds are working, vacuum in the center stack is A-OK, and I can feel the heater flap moving inside the box. I have an early-ish VIN that has a low pressure switch but no high pressure hub.

So, the A/C is cooling, the compressor is cycling - but it's not like "whoa"

Is there physics surrounding the low ambient temperatures that is making me see this behavior, or is there something wrong that needs investigating here? I converted the A/C to R-134 some time ago and replaced every component except the evaporator. It pulled a tight vacuum after an initial leak was discovered and I haven't touched it since. I don't have my gauges (on loan to another owner) to get any pressure readings - but is it possible that I'm just dumb for trying to air condition cold air? Or...

Also, I should say that due to the slope of my driveway, I do tend to end up with some water in my evaporator box when I wash the car. Long ago I learned that if I park with the nose facing down I can avoid this, but I forgot today. So there may be some water in there, which I have heard can reduce efficiency. I have long thought that the drain tube coming out of my evaporator box is pinched between the body and frame, but I simply cannot find the bugger to prove that. I've tried everything, it isn't visible no matter how much of the car I seem to remove (I mean, I guess I could pull the body off, but... no)

[Bitsyncmaster]

If the evaporator box was full of water, that will limit your cooling. When I put in a new box drain, my AC performance when way up.

[David T]

If the evaporator box was full of water, that will limit your cooling. When I put in a new box drain, my AC performance when way up.

For capacity type questions you really need more instrumentation. At a minimum a manifold gauge set, accurate thermometers and a fan in front of the radiator.
Things that can reduce the cooling capacity:
Air in the system
Not enough or too much refrigerant
Debris blocking the condenser or evap coils
The wrong refrigerant (the system was designed for R-12 not -134 or blends)
A problem with the fan motor or the duct systems not activating correctly.
A problem with the cooling fans (one may be bad, the blades may have come loose)
From your brief description my guess is either air in the system and/or not enough refrigerant. But often it is usually not just 1 thing but a combination all adding up to a loss of capacity.

[jawn101]

If the evaporator box was full of water, that will limit your cooling. When I put in a new box drain, my AC performance when way up.

I remember you saying that a while back, and in more than one thread - that's what led me to try and check it in the first place.

I haven't opened my evap box before (one of about 10 pieces of the car I haven't dismantled yet) and am not really sure of the geometry inside. How far off the bottom is the coil, really? Would I notice the fan acting/sounding strangely if there was water in there? It sounded fine and was blowing strong with no evident moisture from the vents.

[Ron]

$.02

I would confirm the drain is clear and wait until it warms up a bit then use the chart at N:09:01 (be sure to check when it cycles out!)...Then the pressures you get can guide you as to whether it is high/low/contaminated/set wrong.
Expect the 134a pressures to be a bit higher except for low side pressure at cut off, and output temp a little warmer...If you didn't reduce the charge by 10%, it is (was) over charged (also matches cycling out late...but hard to rely on at ~55F).

[hmcelraft]

David T is correct. You cannot know for sure what your problem is, and therefore know what to do, without checking it with the proper tools - which - includes checking to be sure you know what type of refrigerant is in the system. Your system sounds like it has lost some refrigerant gas (classic fast cycling). However, you cannot check and fix it without the tools - and - the skills.

[jawn101]

$.02

I would confirm the drain is clear and wait until it warms up a bit then use the chart at N:09:01 (be sure to check when it cycles out!)...Then the pressures you get can guide you as to whether it is high/low/contaminated/set wrong.
Expect the 134a pressures to be a bit higher except for low side pressure at cut off, and output temp a little warmer...If you didn't reduce the charge by 10%, it is (was) over charged (also matches cycling out late...but hard to rely on at ~55F).

Thanks Ron, I was hoping you'd show up - I know you're our A/C guru :)

So would you agree, at a minimum, that observing and judging A/C behavior at these temperatures may have been a little silly?

Further to that... are there *any* suggestions on how I might get at the drain? I know there's the hard plastic funnel into the tub, but from there I cannot find anything. I pulled the fuel tank closing plate to try and reach around, no dice. Took all the inspection panels out of the trunk and I can't see it there either. I also tried running a snake through the drain from inside the box by removing the blower fan, but my wrists just don't bend that way and I didn't get anywhere.

[Ron]

Thanks Ron, I was hoping you'd show up - I know you're our A/C guru :) Not.


So would you agree, at a minimum, that observing and judging A/C behavior at these temperatures may have been a little silly?Not really...You can get an idea (with gauges), I like to set it up for mid-range/average ambient temps (or max if in torrid zones ;-)


Further to that... are there *any* suggestions on how I might get at the drain? I know there's the hard plastic funnel into the tub, but from there I cannot find anything. I pulled the fuel tank closing plate to try and reach around, no dice. Took all the inspection panels out of the trunk and I can't see it there either. I also tried running a snake through the drain from inside the box by removing the blower fan, but my wrists just don't bend that way and I didn't get anywhere.I've seen a very few (no problems) and I hear about them having a lot of different setups. I'd call Dave S or someone like Rob who have seen 100's, I guess.


Hmmm...Seems you could backtrack and find it??

[jawn101]

Not.

Not really...You can get an idea (with gauges), I like to set it up for mid-range/average ambient temps (or max if in torrid zones ;-)

I've seen a very few (no problems) and I hear about them having a lot of different setups. I'd call Dave S or someone like Rob who have seen 100's, I guess.


Hmmm...Seems you could backtrack and find it??

Roger. Will reclaim my gauges at some point and run it down with pressures, the right way.

As for the drain, the problem is backtracking from where. I can't access the area that the funnel comes through the tub, and I have no idea where the hose leading from it is - thats the problem.

[DMCMW Dave]

[QUOTE=Ron;192456]Not.

I've seen a very few (no problems) and I hear about them having a lot of different setups. I'd call Dave S or someone like Rob who have seen 100's, I guess.
QUOTE]

Pull the carpet back on the passenger side at the top left (i.e. at the tunnel). At the bottom of the heater box you'll see a shiny black plastic tube about 3/4" diameter. That is the top of the drain funnel, it goes through the floor, necks down to about 1/4 inch and stupidly makes a 90 degree bend between the fiberglass and the frame. You can heat it up with a heat gun aka hair dryer and pull it down off the heater box nipple (careful not to break it!). Then you can go upwards with a wire bent into a hook and see if you can pull out any goop/hair/leaves etc. You need to find the other end of the drain outside (usually near the receiver/dryer bottle) and blow in with compressed air to dislodge any crud in the elbow. Do this with it disconnected so that you don't just blow it back up into the heater box. It can make a mess inside the car so be ready for a cleanup, and cover the carpeting.

[content22207_2]

Cut the hard plastic elbow in half with a hacksaw blade and pull the two pieces out separately. Replace the hard plastic elbow with an ignition coil boot. Fits the evaporator box perfectly (coil boot, not distributor cap boot -- it's slightly larger diameter):

40395

In the future you can easily pop the flexible boot off to clean it out.

Dave McKeen attached a length of hose to his coil boot, but I just let mine run off the frame (condensed A/C water is no different than rain water).

Bill Robertson
#5939

[Bitsyncmaster]

Cut the hard plastic elbow in half with a hacksaw blade and pull the two pieces out separately. Replace the hard plastic elbow with an ignition coil boot. Fits the evaporator box perfectly (coil boot, not distributor cap boot -- it's slightly larger diameter):

40395

In the future you can easily pop the flexible boot off to clean it out.

Dave McKeen attached a length of hose to his coil boot, but I just let mine run off the frame (condensed A/C water is no different than rain water).

Bill Robertson
#5939

+1

If your not seeing water dripping from the drain (In the summer time) then get rid of that drain elbow. It's to much working taking the evaporator box apart. Just cut off the OEM drain and install a new one even if you have to cut a little of the glass tub.

[content22207_2]

Reach into the box with your pinky and make sure the drain hole is clear before popping the boot on.

Bill Robertson
#5939

[David T]

You guys are sending this OP down the wrong path. There is nothing to believe the condensate drain is the problem (at this time anyway).

[DMCVegas]

You guys are sending this OP down the wrong path. There is nothing to believe the condensate drain is the problem (at this time anyway).

And you are absolutely correct. Take a look at this quote by OP:


Also, I should say that due to the slope of my driveway, I do tend to end up with some water in my evaporator box when I wash the car.

You should never ever, EVER end up with water inside of the evaporator box after a car wash. The problem with water here isn't a drain hose being clogged, it's a drain port on the Air Plenum.

The Air Plenum isn't a part that is installed on the car, so don't bother looking for it. It is a cavity in the front firewall, at the bottom of the windsheild which is formed during the construction of the vehicle itself. ALL cars have one.

The purpose of the plenum is simple: It's a box with an open top, and in a recessed area under an overhang there is an opening that connects to a duct that feeds fresh air down to your blower motor. The overhang prevents rain or wash water from falling directly into the vent. For a bit of a visual, here is a look at the Engine Inlet duct on the rear, right of your car:

http://store.delorean.com/images/Product/large/105831.jpg

As you can see here, air comes in through the top, and then gets sucked out of the side to feed the engine, and water falls down to the bottom where it drains out of the pontoon. Keep that in mind.

At the bottom of the plenum, there is a drain hole. The idea is that any water that flows down the windshield during rain or washing will go into this box along with the outside air. Air of course which is lighter than water will be sucked up and pulled into the car. Heavy water will continue down to the bottom of the plenum, and then drains right out of the hole at the bottom. On most cars, this drain dumps right out into the engine compartment. But on the DeLorean, it drains directly on top of the gas tank.

As I said previously, you have a problem with a clogged drain hole in that plenum. Don't worry, it happened to me as well. A bunch of eucalyptus leaves and layers and layers of silt from being a desert car all if it's life led to this. Best case scenario is that you just need to pop the access panel off of the fuel tank (under the spare tire), get a long stick, fill in a little bit of water into the plenum, and then stir the mud up. You might need to aid in the process by poking through the drain hole below the fuel tank and pulling debris out. Even one of those drain clog grabber claws to get small sticks and other trash out works wonders at pulling debris out through the drain or up between the grille. If worse does come to worse, you just need to pull the screen at the bottom of the windshield and just use a small vacuum hose to pull the debris out. Oh, and don't forget to take a look at that Engine Inlet Duct I mentioned previously. Chances are, it's probably got stuff in it too.

As for your underperforminng A/C? Well, you're gonna need to do the following:


Ensure you have barrier hoses, or else you're gonna be recharging your system EVERY year!
Check your pressures with a Manifold Gauge.
Adjust your high pressure cut-off switch. The EPA had some guidelines for this, at it was to give the screw a quarter turn to accommodate R134a's pressure difference for optimal cooling efficiency (can't remember which direction though).

[content22207_2]

If Dave Swingle told him to clean out the evaporator box drain (with a bent piece of wire no less), that's good enough for me.

Bill Robertson
#5939

[jawn101]

Wow, a lot of responses here. Thanks to all - and here are some replies.




Pull the carpet back on the passenger side at the top left (i.e. at the tunnel). At the bottom of the heater box you'll see a shiny black plastic tube about 3/4" diameter. That is the top of the drain funnel, it goes through the floor, necks down to about 1/4 inch and stupidly makes a 90 degree bend between the fiberglass and the frame. You can heat it up with a heat gun aka hair dryer and pull it down off the heater box nipple (careful not to break it!). Then you can go upwards with a wire bent into a hook and see if you can pull out any goop/hair/leaves etc. You need to find the other end of the drain outside (usually near the receiver/dryer bottle) and blow in with compressed air to dislodge any crud in the elbow. Do this with it disconnected so that you don't just blow it back up into the heater box. It can make a mess inside the car so be ready for a cleanup, and cover the carpeting.

I know this process from earlier posts of yours, the problem is that I just cannot find the other end of the drain hose. That's why I think the box doesn't drain (I have never seen water under my car when running the A/C) - the hose is pinched somewhere along the line.

Which brings me to....


Cut the hard plastic elbow in half with a hacksaw blade and pull the two pieces out separately. Replace the hard plastic elbow with an ignition coil boot. Fits the evaporator box perfectly (coil boot, not distributor cap boot -- it's slightly larger diameter):

40395

In the future you can easily pop the flexible boot off to clean it out.

Dave McKeen attached a length of hose to his coil boot, but I just let mine run off the frame (condensed A/C water is no different than rain water).

Bill Robertson
#5939

Actually not a bad idea at all. I'm not sure if I can contort myself this way but that drain being hard instead of flexible is dumb in the first place. This is a pretty elegant solution, if I can make it happen.


And you are absolutely correct. Take a look at this quote by OP:



You should never ever, EVER end up with water inside of the evaporator box after a car wash. The problem with water here isn't a drain hose being clogged, it's a drain port on the Air Plenum.

The Air Plenum isn't a part that is installed on the car, so don't bother looking for it. It is a cavity in the front firewall, at the bottom of the windsheild which is formed during the construction of the vehicle itself. ALL cars have one.

The purpose of the plenum is simple: It's a box with an open top, and in a recessed area under an overhang there is an opening that connects to a duct that feeds fresh air down to your blower motor. The overhang prevents rain or wash water from falling directly into the vent. For a bit of a visual, here is a look at the Engine Inlet duct on the rear, right of your car:

http://store.delorean.com/images/Product/large/105831.jpg

As you can see here, air comes in through the top, and then gets sucked out of the side to feed the engine, and water falls down to the bottom where it drains out of the pontoon. Keep that in mind.

At the bottom of the plenum, there is a drain hole. The idea is that any water that flows down the windshield during rain or washing will go into this box along with the outside air. Air of course which is lighter than water will be sucked up and pulled into the car. Heavy water will continue down to the bottom of the plenum, and then drains right out of the hole at the bottom. On most cars, this drain dumps right out into the engine compartment. But on the DeLorean, it drains directly on top of the gas tank.

As I said previously, you have a problem with a clogged drain hole in that plenum. Don't worry, it happened to me as well. A bunch of eucalyptus leaves and layers and layers of silt from being a desert car all if it's life led to this. Best case scenario is that you just need to pop the access panel off of the fuel tank (under the spare tire), get a long stick, fill in a little bit of water into the plenum, and then stir the mud up. You might need to aid in the process by poking through the drain hole below the fuel tank and pulling debris out. Even one of those drain clog grabber claws to get small sticks and other trash out works wonders at pulling debris out through the drain or up between the grille. If worse does come to worse, you just need to pull the screen at the bottom of the windshield and just use a small vacuum hose to pull the debris out. Oh, and don't forget to take a look at that Engine Inlet Duct I mentioned previously. Chances are, it's probably got stuff in it too.

As for your underperforminng A/C? Well, you're gonna need to do the following:


Ensure you have barrier hoses, or else you're gonna be recharging your system EVERY year!
Check your pressures with a Manifold Gauge.
Adjust your high pressure cut-off switch. The EPA had some guidelines for this, at it was to give the screw a quarter turn to accommodate R134a's pressure difference for optimal cooling efficiency (can't remember which direction though).


I understand that water should not be in the evap box. As I said in my original post, this happens only when I wash the car on my steep driveway with the nose pointed in the air - the water does not reach the drain hole (which is not plugged, BTW) before it gets into the evaporator box. It does not occur under normal driving conditions.

I have barrier hoses - every part in this system save the evaporator itself has been replaced and spec'd to run R134a. I also do not have a high-pressure hub, this car was built without one and I didn't think to add one when I rebuilt the system.

Sounds like I need to check the pressures, first and foremost - which I am not surprised by (everyone seems really quick to assume I don't know how to do that, despite my saying repeatedly that I own gauges but have just loaned them out!) - and secondary to that, I will try and verify that my evaporator box does indeed drain properly.

[content22207_2]

Robert is correct that if your windshield plenum drain isn't clear water can fill the evaporator box through the fresh air door. Once inside the evaporator box there are three ways out: normal condensation drain (hard plastic elbow), blower motor cooling hose, or the ducting itself. If the condensation drain is clear any water that happens to find its way into the box will drain right back out.

Condensation drain is the lowest point in the box. Blower motor hose is next highest. Ducts are the highest,

Pull your resistor grid off to see if it is rusty. If it is, you probably have water backing up into the evaporator box. Water backing up into the box will also rust your blower motor bearings if it runs down the blower motor hose.

Bottom line: a flexible rubber connection to the condensation drain is a significant maintenance improvement. Several of us have done the mod. Dave Swingle also likes it, although he's not too crazy about me just letting water wash off the frame (he prefers a hose attached to the coil boot, as Dave McKeen has done).

Bill Robertson
#5939

[PJ Grady Inc.]

This sounds like a simple case of low Freon to me and a quick check with A/C gauges would confirm it. As David said you'll need to determine what type of gas is present but hopefully R12 or 134A. The next likely cause is a partially clogged orifice tube.

As for a clogged HVAC box drain, which is common, you access it from the passenger side behind the radio console where the box rests on the fiberglass hump over the frame center box section. Pull the carpet back and look (with a flashlight) for the nipple going through the body by the blue heater cable. Heat the shiny plastic drain tube with a hair dryer and using a long needle nose pliers carefully pull the tube away from the opening towards the passenger foot well area. Take an "Exacto" style mini-saw and carefully cut about 1/4" off the bottom of the plastic box drain outlet. Remove no more than that as its only 3/4" long by 3/4 wide. you'll need it to reattach the hose to when finished blowing out any debris. This will allow you to return the hose back into position without damage. Use an air blower with extension pipe to insert in the tube and blow through the hose which should dislodge the debris towards the outside. Now heat the hose again, but not too much, and use the needle-nose to nudge it back in position over the heater drain outlet. The other end of the hose hose usually rests on the the passenger frame rail by the fuel tank and can be accessed through the fuel pump opening by removing the inspection cover or by removing the R/F wheel. Contrary to what's been said it's sometimes necessary to also blow back gently through this end to disperse accumulated debris back from the top of the drain outlet into the heater box. If this is necessary it may have to be repeated a few times over an extended period to remove debris that may re-accumulate over time but I've never damaged the internals this way and it will be much easier the next time with the shortened drain outlet and experience gained on the first attempt. The only special tools needed are the compressed air with a long blower nozzle and a mini-saw. I have found this to be the best and safest way to clear the box. The body drain plenum above the fuel pump should also be checked and cleared but that's a subject for another day as the shop beckons.
Rob

[DMCVegas]

Wow, a lot of responses here. Thanks to all - and here are some replies.

I know this process from earlier posts of yours, the problem is that I just cannot find the other end of the drain hose. That's why I think the box doesn't drain (I have never seen water under my car when running the A/C) - the hose is pinched somewhere along the line.

I think that I might know where some of this confusion is setting in... There are TWO drains on the A/C & Heating system for the DeLorean. The first one is inside of the Air Plenum at the bottom of the windsheild. The Second is at the lowest point of the evaporator/blower assembly box.

As I said before, the Air Plenum is designed to separate water (rain or wash) from the fresh air being pumped into the Evaporator/Blower Assembly. Water goes through a horizontal drain at the bottom, and dumps out onto the top of the gas tank. There is *supposed* to be a plenum hose, but chances are that it may be missing. Pull your access panel for the fuel pump, and then reach up under and behind the lip where the top rivnuts are for the access panel. Push your fingers up against the firewall and you'll feel it. It's just a hole that drains out onto the top of the gas tank. There's supposed to be a hose (part 101957), but it definitely wasn't there on my car. It looks like this:
https://store.delorean.com/images/Product/large/101957.jpg

The Second drain is at the bottom of the evaporator/blower assembly box. It connects up to the Drain Tube (part 105909)
https://store.delorean.com/images/Product/large/105909.jpg
That goes down, and out of the passenger compartment, and then runs down between the outside of right chassis and underbody where it dumps out near the A/C dryer, behind the front, right tire. The entire purpose of this hose is to drain off all condensation that collects from the A/C condenser from humid air. You can see it here, though sometimes it might be shorter, and is a bit more hidden. But this is where it is.
http://www.specialtauto.com/delorean-parts/images/ac-evaporator-drain.jpg

So in the grand scheme of things, we have 3 separate tiers here inside of the car A/C & Heater system. The first one is the highest, and that is the fresh air intake inside of the plenum. The middle Tier is the Blower Motor Assembly. The lowest level is going to be the Evaporator.

Water drains out of the Air Plenum AND it drains out of the Evaporator Box. Water NEVER gets near the blower motor itself.

If you are driving with the Air Conditioning on, with no rain and you get a wet passenger side carpet, then you know that the drain system for the Evaporator is clogged. Condensation cannot drain out.
If you are washing the car (at any angle) and you get a soaked passenger carpet, then you know that the Air Plenum drain is clogged. Why? Water does not run uphill. When you park with the nose facing down the driveway, the Air Plenum is still filling up, but you're keeping the fresh air intake up above water, and the overflow is instead cascading down across the bottom of the windshield.

If you DO have the plenum drain hose, there is a chance that the rubber may be stuck together and preventing the Plenum from draining. Given that it's above the fuel tank, it's not meant to be rigid rubber. It supposed to be flimsy so that the weight of water will push it open, but the vacuum won't allow it to suck air in. Kind of like a check valve. It supposed to prevent fumes and the like from being sucked into the passenger compartment. But on a rear-engined car, it's not really a problem Unless you have a leak in the gas tank. Like I did with a bad TankZilla unit (but that's a long story).

You can do this!

[jawn101]

I think that I might know where some of this confusion is setting in... There are TWO drains on the A/C & Heating system for the DeLorean. The first one is inside of the Air Plenum at the bottom of the windsheild. The Second is at the lowest point of the evaporator/blower assembly box.

As I said before, the Air Plenum is designed to separate water (rain or wash) from the fresh air being pumped into the Evaporator/Blower Assembly. Water goes through a horizontal drain at the bottom, and dumps out onto the top of the gas tank. There is *supposed* to be a plenum hose, but chances are that it may be missing. Pull your access panel for the fuel pump, and then reach up under and behind the lip where the top rivnuts are for the access panel. Push your fingers up against the firewall and you'll feel it. It's just a hole that drains out onto the top of the gas tank. There's supposed to be a hose (part 101957), but it definitely wasn't there on my car. It looks like this:
https://store.delorean.com/images/Product/large/101957.jpg

The Second drain is at the bottom of the evaporator/blower assembly box. It connects up to the Drain Tube (part 105909)
https://store.delorean.com/images/Product/large/105909.jpg
That goes down, and out of the passenger compartment, and then runs down between the outside of right chassis and underbody where it dumps out near the A/C dryer, behind the front, right tire. The entire purpose of this hose is to drain off all condensation that collects from the A/C condenser from humid air. You can see it here, though sometimes it might be shorter, and is a bit more hidden. But this is where it is.
http://www.specialtauto.com/delorean-parts/images/ac-evaporator-drain.jpg

So in the grand scheme of things, we have 3 separate tiers here inside of the car A/C & Heater system. The first one is the highest, and that is the fresh air intake inside of the plenum. The middle Tier is the Blower Motor Assembly. The lowest level is going to be the Evaporator.

Water drains out of the Air Plenum AND it drains out of the Evaporator Box. Water NEVER gets near the blower motor itself.

If you are driving with the Air Conditioning on, with no rain and you get a wet passenger side carpet, then you know that the drain system for the Evaporator is clogged. Condensation cannot drain out.
If you are washing the car (at any angle) and you get a soaked passenger carpet, then you know that the Air Plenum drain is clogged. Why? Water does not run uphill. When you park with the nose facing down the driveway, the Air Plenum is still filling up, but you're keeping the fresh air intake up above water, and the overflow is instead cascading down across the bottom of the windshield.

If you DO have the plenum drain hose, there is a chance that the rubber may be stuck together and preventing the Plenum from draining. Given that it's above the fuel tank, it's not meant to be rigid rubber. It supposed to be flimsy so that the weight of water will push it open, but the vacuum won't allow it to suck air in. Kind of like a check valve. It supposed to prevent fumes and the like from being sucked into the passenger compartment. But on a rear-engined car, it's not really a problem Unless you have a leak in the gas tank. Like I did with a bad TankZilla unit (but that's a long story).

You can do this!

Yes, I know all that. No confusion here. The plenum drain is free and clear, unblocked and unencumbered by the drain hose - just a big, open, clearly unblocked hole in the fiberglass. The evap box drain is the one I suspect may be clogged, though everyone seems to agree that this concern is likely only tangentially related to my cooling performance issues.

[DMCVegas]

Yes, I know all that. No confusion here. The plenum drain is free and clear, unblocked and unencumbered by the drain hose - just a big, open, clearly unblocked hole in the fiberglass. The evap box drain is the one I suspect may be clogged, though everyone seems to agree that this concern is likely only tangentially related to my cooling performance issues.

And I would agree. Clearing that drain tube is usually pretty easy. Check for kinks, possibly disconnect it and blow it out, or just vacuum it out.

It however still wouldn't account for leaks when washing the car, and that then get avoided when parking at an angle. If the plenum is clear, then no water would be entering through that path. You have a leak elsewhere.

[content22207_2]

Depends where the leak is coming from. If the condensation drain is clogged, and water builds up inside the evaporator box, it will eventually come out the blower motor hose. Definitely comes out the blower motor hose if the condensation drain is clogged while you're running the A/C (look for tell tale rust stains on the carpet below the blower motor).

Remember: when the car is pointed uphill, the windshield plenum drain is pointed uphill as well. Steep enough hill will put the fresh air door below the windshield plenum drain. Drain isn't at the bottom of the plenum anyway -- feels like there's 1/4" to 1/2" from the hole to the bottom of the plenum.

Bill Robertson
#5939

[jawn101]

Okay, an update. I used Rob's heat gun trick to pry the funnel off the nipple from the evap box. Pushing a little air through from that end allowed me to finally locate the drain hose and fish it out so I could see it. Then I pushed some air through from that end as well. No evidence of blockage at all, air flowed freely with no debris coming out. Reattached the funnel with the hose now positioned where I can see it, on the fuel tank. Drove around with the A/C on full blast for a half hour or so. No water from the hose at all. But it's very low %RH here. Vent air was blowing about 52 degrees, down from about 63 ambient. Going to head out to Clint's place this weekend and hook up my gauges to test pressures, etc.

[Ron]

Going to head out to Clint's place this weekend and hook up my gauges to test pressures, etc.

'bout time! :neener:


..don't forget to take readings when the clutch cycles OUT.

[jawn101]

'bout time! :neener:


..don't forget to take readings when the clutch cycles OUT.

Roger that. Just been too busy to make any time to really work on anything - this has been my first chance!

[David T]

One way to test the drain is to remove the fan motor and pour water into the box and watch it come out the drain.

[jawn101]

One way to test the drain is to remove the fan motor and pour water into the box and watch it come out the drain.

Great idea - I will do that.