Insulated Evaporator Box *** SPLIT From What have you done to your D today ??? **

[jawn101]

Drove it to work this morning. Ambient temperature was 85°F, heat index was 97°F. Figured it'd be a good workout for the a/c. Had to turn it down to speed 2 because I was getting too cold! :woot:

I do need to put that foam on the evaporator box, though... my passenger floormat was wet from the dripping condensation after the half-hour drive.

Congrats man :)

I'm starting to think I need to get my system professionally flushed and re-filled. I rebuilt it a few years ago, replaced everything but the evaporator and condenser and it works and blows cold, but I never have that "meat locker, turn it down" experience.

Weird since I've measured the vent temps at 30 degrees before. I wonder what the deal is.

[Farrar]

If you're not leaking, but you don't have cold air, put gauges on it and see what you can find. If the high side needle has giant swings and the low side needle barely moves, you could have a blocked or dirty orifice tube.

[jawn101]

If you're not leaking, but you don't have cold air, put gauges on it and see what you can find. If the high side needle has giant swings and the low side needle barely moves, you could have a blocked or dirty orifice tube.

Yeah, I've checked the pressures before too. They look good. The air is cold but it just seems like it doesn't really make it to me, or the overall temperature inside the car is just too high. I need to get those windows tinted and see if it makes any difference at some point.

Going to try the gauges again tonight actually. Just for fun. I might get the whole thing professionally evacuated, flushed, vacuumed and refilled at some point.

[WelmoedJ]

Drove it to work this morning. Ambient temperature was 85°F, heat index was 97°F. Figured it'd be a good workout for the a/c. Had to turn it down to speed 2 because I was getting too cold! :woot:

I do need to put that foam on the evaporator box, though... my passenger floormat was wet from the dripping condensation after the half-hour drive.

If condensation is dripping on the floor you may have a clogged drain pipe.

[Farrar]

If condensation is dripping on the floor you may have a clogged drain pipe.

I cleaned the drain before I re-installed the evaporator, but I'll check to make sure I am dripping on the ground like I should. My car is one of the early ones without the foam on the evaporator box. I hear that installing that foam cures the "passenger has wet feet" experience. Which type of foam to get, though?

[WelmoedJ]

I cleaned the drain before I re-installed the evaporator, but I'll check to make sure I am dripping on the ground like I should. My car is one of the early ones without the foam on the evaporator box. I hear that installing that foam cures the "passenger has wet feet" experience. Which type of foam to get, though?

If there has to be foam, it has to be on the inside I presume.
My airbox doesn't have it at least not on the outside.
Never checked or needed to check the inside, though.

Kind of foam? Not sure, but probably something alike what's on the inside of the vinyl of the center console and doors (thin layer, some 2 mms).

[Jack]

Yeah, I've checked the pressures before too. They look good. The air is cold but it just seems like it doesn't really make it to me, or the overall temperature inside the car is just too high. I need to get those windows tinted and see if it makes any difference at some point.

Going to try the gauges again tonight actually. Just for fun. I might get the whole thing professionally evacuated, flushed, vacuumed and refilled at some point.

I have to agree about the sunlight being the main cause of AC struggling.
As soon as its over cast or the car is not in direct sunlight, the car instantly starts to cool down.
It's like the AC is trying to fight the greenhouse effect of our windshields

[jawn101]

I cleaned the drain before I re-installed the evaporator, but I'll check to make sure I am dripping on the ground like I should. My car is one of the early ones without the foam on the evaporator box. I hear that installing that foam cures the "passenger has wet feet" experience. Which type of foam to get, though?

I get the wet feet syndrome periodically too. I can't get anywhere near my stupid drain tube, it's crammed in between the frame and the body. But I have cleaned the evap box and it wasn't full of crap (next to none in fact) so my hope is that it's clear. Do you have more info about the foam you're referring to? I'm all for trying whatever this fix is to stop the water on the floor.


I have to agree about the sunlight being the main cause of AC struggling.
As soon as its over cast or the car is not in direct sunlight, the car instantly starts to cool down.
It's like the AC is trying to fight the greenhouse effect of our windshields

No joke. I'm going to get some invisible ceramic heat rejecting film installed and see if it helps.

[Farrar]

If there has to be foam, it has to be on the inside I presume.
My airbox doesn't have it at least not on the outside.

From John Hervey's website (box is upside down):

http://www.specialtauto.com/delorean-parts/images/ac-evaporator-box.jpg

Found elsewhere here on DMCTalk:

http://i.imgur.com/0x612.jpg

My car shows no evidence that anything was ever there, either. I suspect it's something introduced after my VIN.

[Farrar]

I can't get anywhere near my stupid drain tube, it's crammed in between the frame and the body. But I have cleaned the evap box and it wasn't full of crap (next to none in fact) so my hope is that it's clear.

If you replace the drain tube with a straight boot from an ignition coil wire, you have a much softer connector between the box and the body. Attach a length of tubing to it and you can throw the stock tube away. Then, periodically, you can remove the boot and tube and check for debris/blow out with compressed air. But you're right -- it should be pretty clean in your case.

[dmc6960]

The "condensation foam" goes on the outside of the evaporator box, it does not go on the inside. Wet feet can come from drips from condensation on the outside of the evaporator box. Soaked feet come from a plugged up drain tube.

Heat-rejecting window tint will be a huge gain for the AC performance. However there could still be other factors why the whole cabin doesn't cool well. Do you know 100% your evaporator is not plugged up with debris? Do you know 100% that your fan is blowing in the correct direction and you have a correctly oriented squirrel cage? Have you sealed up around the door vents or have them capped at all? FYI, while capping the door vents may increase the airflow through the center vents, the whole systems is choked reducing the total amount of heat sunk. This will result in a cold face if they are blowing on you but everything else will still be uncomfortably hot.

When you have cold air, but a warm cabin, you need more airflow.

[jawn101]

From John Hervey's website (box is upside down):

http://www.specialtauto.com/delorean-parts/images/ac-evaporator-box.jpg

Found elsewhere here on DMCTalk:

http://i.imgur.com/0x612.jpg

My car shows no evidence that anything was ever there, either. I suspect it's something introduced after my VIN.

So I definitely don't have the foam wrap around the evap box, that looks downright weird to me. But there should definitely be foam on the door in the upper right of the second photo. However, I don't think that would have any effect on condensation forming. All the condensation would occur and be localized within the evap box itself.


If you replace the drain tube with a straight boot from an ignition coil wire, you have a much softer connector between the box and the body. Attach a length of tubing to it and you can throw the stock tube away. Then, periodically, you can remove the boot and tube and check for debris/blow out with compressed air. But you're right -- it should be pretty clean in your case.

Yarg. I tried cutting the spout away from inside the car and couldn't make it happen. Just couldn't get my hands in there, and the plastic is remarkably strong. And the actual hose after that spout was the one I mean is trapped between the frame and body.

[Bitsyncmaster]

I get the wet feet syndrome periodically too. I can't get anywhere near my stupid drain tube, it's crammed in between the frame and the body. But I have cleaned the evap box and it wasn't full of crap (next to none in fact) so my hope is that it's clear. Do you have more info about the foam you're referring to? I'm all for trying whatever this fix is to stop the water on the floor.



No joke. I'm going to get some invisible ceramic heat rejecting film installed and see if it helps.

One of the first things I did was pull the AC box and clean it out and put new foam on the box doors. My AC never cooled very well until I cut out that stock drain tube and did the new drain. Then the AC work so much better.

You can cut away that old drain if you pull the carpet and get to the old drain "boot" with an exato knife. Then your new "boot" (ignition coil boot) can be worked over the drain pipe. I added a new hose to drain below the frame by drilling a hole in the floor and using a right angle boot.

[jawn101]

The "condensation foam" goes on the outside of the evaporator box, it does not go on the inside. Wet feet can come from drips from condensation on the outside of the evaporator box. Soaked feet come from a plugged up drain tube.

Heat-rejecting window tint will be a huge gain for the AC performance. However there could still be other factors why the whole cabin doesn't cool well. Do you know 100% your evaporator is not plugged up with debris? Do you know 100% that your fan is blowing in the correct direction and you have a correctly oriented squirrel cage? Have you sealed up around the door vents or have them capped at all? FYI, while capping the door vents may increase the airflow through the center vents, the whole systems is choked reducing the total amount of heat sunk. This will result in a cold face if they are blowing on you but everything else will still be uncomfortably hot.

When you have cold air, but a warm cabin, you need more airflow.

Good insights Jim. It's never been a case of 'soaked' - more like a small wet spot. I'd put money on the condensation rather than the plugged tube. One of these days I'll get that tube untangled from the frame and see what can be done.

Yes, I know my fan blows the right way and the cage is correct. The door vents are sealed up very well - I redid the entire assembly on both sides with fat A/C weatherstripping and high-temp metallic tape. I have heard that capping the outlets isn't the best idea so that's why I went with the restoration of the existing vent system.

I'm also pretty sure the heat-rejecting tint will help enormously. But I haven't experienced it myself yet. This is turning into a whole separate thread for me and The Voice over here.

[Farrar]

I have heard that capping the outlets isn't the best idea so that's why I went with the restoration of the existing vent system.

+1

When I had the HVAC box out to replace the evaporator, I put new foam on all of the air routing flaps/doors. Next time I have the door panels off, I'm sealing up the area around the door vents, too. I got a good seal between the body ducting and the door ducting by simply pulling the ducts out of the knee pads ever so slightly at the bottom (your mileage may vary -- every DeLorean has different door fitment).

Hey Jon, start an a/c thread, will ya? ;)

[Farrar]

I tried cutting the spout away from inside the car and couldn't make it happen.

Do you have an old tomato knife? A long, serrated blade should do the trick.

[jawn101]

Hmm. Not sure. I'll give it another try one day. I tried the A/C on the way home today and it was quite chilly. I really think the problem is that I'm always too hot no matter what, combined with the brutal CA sun where I live.

[vwdmc16]

Yeah Just get that IR tint Jon!

[kings1527]

Yeah Just get that IR tint Jon!

+1 HUGE difference!

[jawn101]

+1 HUGE difference!

Alright alright! :) I will make an appointment with the guy in the next couple weeks. I do still think my drain hose is pinched somewhere.

[Farrar]

I know California and Texas have a contest going for which state is hotter (are they going for sympathy or machismo?), but I will say that before my a/c quit working, I could get into my car, which I measured as having an internal temperature of ~155°F, when the ambient temperature was 100° and the heat index was 112°F, and feel significant cooling within about five minutes of switching on the a/c. And my car just has a plain old dark tint in it, which is several years old and was probably done on the cheap by a previous owner. If you get your a/c working AND have your windows tinted, you should be able to cool off even faster. I'm looking forward to seeing the results.

[jawn101]

(are they going for sympathy or machismo?)

Both!!! :)

When I moved here, I was shocked by how laser-intense the sun is. Being a northeast native myself, I was used to a "softer" sun combined with humidity. Here we have this oft-lauded "dry heat" but the intensity of the sun is really the incredible thing. You can walk out of a building into a parking lot and instantly feel like the sky is trying to burn you like an ant under a magnifying glass. Get in a standard D and the effect is even further amplified by the uncoated glass. You need sunscreen on your arms *inside* the car, and even when it's hotter than hell my wife still wears a light jacket in the car just to keep the death-ray off her.

I will definitely report back once I get the coatings done.

[Grover]

One of the first things I did was pull the AC box and clean it out and put new foam on the box doors. My AC never cooled very well until I cut out that stock drain tube and did the new drain. Then the AC work so much better.

You can cut away that old drain if you pull the carpet and get to the old drain "boot" with an exato knife. Then your new "boot" (ignition coil boot) can be worked over the drain pipe. I added a new hose to drain below the frame by drilling a hole in the floor and using a right angle boot.

Why would creating a better drain tube/drain system cause the A/C to operate better? Less moisture in the box??

[Bitsyncmaster]

Why would creating a better drain tube/drain system cause the A/C to operate better? Less moisture in the box??

The evaporator sits in bottom of the box. If you have an inch or two of water in the box, the air can not flow past those fins under water.

[jawn101]

The evaporator sits in bottom of the box. If you have an inch or two of water in the box, the air can not flow past those fins under water.

So here's something else I never understood. Isn't the fan motor at the lowest point of the box? If you have 2" of water, wouldn't the motor be entirely submerged? I had my motor out recently when I cleaned my evap box and there was not even a hint of rust or moisture on the blower itself. Does that mean water isn't collecting there, or what?

[Farrar]

Isn't the fan motor at the lowest point of the box?

No. The box slopes down toward the center of the car.

[jawn101]

No. The box slopes down toward the center of the car.

Hmm. I guess that makes sense, since that's where the drain is. Duh...

[dmc6960]

So here's something else I never understood. Isn't the fan motor at the lowest point of the box? If you have 2" of water, wouldn't the motor be entirely submerged? I had my motor out recently when I cleaned my evap box and there was not even a hint of rust or moisture on the blower itself. Does that mean water isn't collecting there, or what?

The fan is one of the highest points. You'll get water pouring out of the heater vents or the seam between the box halfs long before it could make its way to the blower. By that point anyway the evaporator would be flooded around and could no longer produce additional significant water through the de-humidification process of the high CFM airflow.

[jawn101]

Roger. So the occasional drips are due to the plastic box sweating, then? And the foam pads combat that by just absorbing the sweat?

Is there a way to retrofit the box while its still in the car? :)

Along the same lines - the water that comes in through the fresh air hole under the windscreen cowl also drains through the evap box drain at the center of the car, right? When I wash the car I frequently get water from what appears to be the evap box. Wondering if that could also be indicative of a plugged drain.

[dmc6960]

Roger. So the occasional drips are due to the plastic box sweating, then? And the foam pads combat that by just absorbing the sweat?
Not quite. The drips are indeed from the cold plastic sweating. The foam pads dont absorb the water though, they prevent it from happening by providing an insulation layer from the cold.


Is there a way to retrofit the box while its still in the car? :)
Yes, just reach up and stick it on everything you see on the evaporator half. The rear may be more difficult to get to, but its possible.


Along the same lines - the water that comes in through the fresh air hole under the windscreen cowl also drains through the evap box drain at the center of the car, right? When I wash the car I frequently get water from what appears to be the evap box. Wondering if that could also be indicative of a plugged drain.
No, there is a real drain for the windshield/fresh air intake. Its a small hole which dumps the water directly on top of the fuel pump. Nice eh? It can be a source of clogging with leaves and other debris. When this happens the water will backup through the fresh air intake and start flooding out the blower, evaporator box, and the passenger floorboard.

[jawn101]

Fascinating. I'm going to look for that drain tonight. Anyone have a picture of it? I screened over my intake to prevent crap getting in but that doesn't mean the drain wasn't already clogged.

[dmc6960]

Go to 7:15 in this video Josh recently posted...


http://www.youtube.com/watch?v=S4WLZAo7XZY

[jawn101]

Go to 7:15 in this video Josh recently posted...


http://www.youtube.com/watch?v=S4WLZAo7XZY

Hahahaha.... hahaha...

OK, sorry. I can't believe I never noticed that massive, raw hole in the fiberglass before. Got it. That should be easy enough to find and clean out. What a stupid design.

Anyway, I just took me a drive. I busted out Ikea's finest oven thermometer and took it along for the ride. Crammed the probe way down inside the center vents and monitored the temp on max A/C, fan speed 4, temp dial to full cold.

Here's the temp with the car off, parked in the garage. Ambient inside the vents. 82F
http://dmctalk.org/attachment.php?attachmentid=21059&d=1375918534

Here's the ambient outside temperature, 86F
http://dmctalk.org/attachment.php?attachmentid=21062&d=1375918547

Here's the temp with the A/C pumping full blast, at idle at a stoplight after about 2 minutes of driving. 50F
http://dmctalk.org/attachment.php?attachmentid=21060&d=1375918539

And finally, here's the temp with the A/C at full blast and the car going 70 on a highway. 46F. It held steady at 46 the whole rest of the trip. The temp inside the door vents was about 48F.
http://dmctalk.org/attachment.php?attachmentid=21061&d=1375918542

It's somewhat overcast today and the sun isn't nearly as brutal, so I was quite comfy. I know there are formulas for calculating stuff like this, is a 40 degree drop more or less "normal" for a fully converted system?

[Farrar]

They say 40 degrees below ambient is what you should aim for.

For example: today, my a/c vents in the Chrysler were blowing at about 62°F. This was not quite 40° below the 101°F outside. (Yeah, I know it's hotter in Texas and California -- you poor little things, or man up and deal with it, or something.)

[jawn101]

They say 40 degrees below ambient is what you should aim for.

For example: today, my a/c vents in the Chrysler were blowing at about 62°F. This was not quite 40° below the 101°F outside. (Yeah, I know it's hotter in Texas and California -- you poor little things, or man up and deal with it, or something.)

LOL... we surely did miss your wit during your hiatus, Farrar.

So I guess the sun is really a major comfort factor after all. I probably will still insulate the evaporator box though, to try and stop the sweating. Is that foam of Hervey's anything special or is it just something you can get any old place?

[Farrar]

LOL... we surely did miss your wit during your hiatus, Farrar.

So I guess the sun is really a major comfort factor after all. I probably will still insulate the evaporator box though, to try and stop the sweating. Is that foam of Hervey's anything special or is it just something you can get any old place?

Thanks. :)

I plan on insulating my evaporator box, as well.

There's two schools of thought on the foam:

1. you want open-cell foam to absorb the moisture quickly and then let it evaporate slowly.
2. you want closed-cell foam because if the moisture stays in there too long it will grow mold/mildew.

I still haven't made the decision yet.

[jawn101]

Thanks. :)

I plan on insulating my evaporator box, as well.

There's two schools of thought on the foam:

1. you want open-cell foam to absorb the moisture quickly and then let it evaporate slowly.
2. you want closed-cell foam because if the moisture stays in there too long it will grow mold/mildew.

I still haven't made the decision yet.

Well, so Jim said above that:

Not quite. The drips are indeed from the cold plastic sweating. The foam pads dont absorb the water though, they prevent it from happening by providing an insulation layer from the cold.

So does the open vs closed really apply?