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Username Post: '00 C2500 A/C Condensation Leak Inside Cab        (Topic#361445)
djackson210 
Poster
Posts: 86

Age: 37
Loc: San Antonio, Texas
Reg: 01-31-19
06-20-20 08:15 AM - Post#2796771    

My truck is a '00 OBS C2500 CCSWB.

The A/C box is leaking inside where it meets the firewall. I attached a photo for further clarification. It's definitely condensation. It's cold clear water, no anti freeze.

The A/C drain line isn't clogged, it makes a nice puddle under the truck & I can see it actively dripping as the truck & A/C are running.

This is a unique problem to me, never heard of or seen one quite like it. Anyone ever encounter this? If so, how did you solve it?

Right now I'm just keeping a rolled up micro fiber towel stuffed under there to absorb the water. But I'd love to fix it permanently.

Fingers crossed I don't have to tear the whole entire dash apart to replace the gasket where the plastic box meets the interior firewall.




'91 Chevy C1500 SC LWB
'00 Chevy C2500 CC SWB


Edited by djackson210 on 06-20-20 08:17 AM. Reason for edit: No reason given.

 
Mcrado 
Newbie
Posts: 1

Reg: 06-20-20
06-22-20 06:49 PM - Post#2796947    
    In response to djackson210

...baffling, for sure. The only thing I can guess is that the drain is partially plugged, so drains some of the condensation but can't keep up when hot/humid(?). Mc



 
wagonman100 
Super Senior Member
Posts: 14534
wagonman100
Loc: Baltimore, MD
Reg: 11-27-04
06-22-20 07:44 PM - Post#2796955    
    In response to Mcrado

  • Mcrado Said:
...baffling, for sure. The only thing I can guess is that the drain is partially plugged, so drains some of the condensation but can't keep up when hot/humid(?). Mc



That was my thought as well.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
djackson210 
Poster
Posts: 86

Age: 37
Loc: San Antonio, Texas
Reg: 01-31-19
06-23-20 07:13 AM - Post#2796984    
    In response to wagonman100

Thanks for the suggestions folks. Whenever it stops raining cats & dogs here I'll go back out to the truck & blow some compressed air up the drain line to see if it helps any at all. Maybe a coat hanger too.

It's just so perplexing because I can watch the condensation actively dripping out of the drain line. I'll report back if I can get anything sorted out on it. Thanks again!

'91 Chevy C1500 SC LWB
'00 Chevy C2500 CC SWB


 
someotherguy 
Senior Moderator
Posts: 29170
someotherguy
Age: 50
Loc: Texas
Reg: 08-01-03
06-23-20 08:06 AM - Post#2796989    
    In response to djackson210

That lower cover (heater core access panel) is not open to the evaporator core area, but, if it's humid enough where you're at (it sure is here in Houston) there can still be enough condensation build-up on the opposite side of the plastic around the evaporator that it can drip down onto the lower cover for the heater core, and then it would only be able to escape where you're seeing it come out as it's the lowest point of the area.

If it helps to picture what may be happening, with that lower cover removed, the evaporator housing is still sealed off to drain from the nipple that protrudes through the firewall into the engine bay.

Heater core access cover removed:


Note the rib in the plastic at the bottom of the evap housing; this is the drain line. The yellow circles of course are the screw locations for the lower cover.


The only other way I can imagine much condensate is finding its way to inside your firewall would be if the drain nipple is cracked or possibly rubbed through from the firewall sheetmetal, though it doesn't seem likely as it has that thick foam rubber seal surrounding it and the heater core lines. A crack is possible though if it caught any abuse from the engine bay side.

Or finally, a long shot - but is the rubber 90° elbow still attached to the spout? They're often missing, and it directs the stream away and down from the firewall instead of it possibly wicking back along the nipple and firewall.

(Also, if you look at how the housing and drain nipple are designed you'll see that the seal between the box and firewall isn't going to be your culprit. It's really there for sound and temperature insulating purposes, and so that the plastic of the housing isn't shoved up against the sheetmetal)

Sorry if any of that was rambling or difficult to follow. I work night shifts and am dead tired and a little loopy at the moment.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
djackson210 
Poster
Posts: 86

Age: 37
Loc: San Antonio, Texas
Reg: 01-31-19
06-24-20 06:38 AM - Post#2797077    
    In response to someotherguy

  • someotherguy Said:


The only other way I can imagine much condensate is finding its way to inside your firewall would be if the drain nipple is cracked or possibly rubbed through from the firewall sheetmetal, though it doesn't seem likely as it has that thick foam rubber seal surrounding it and the heater core lines. A crack is possible though if it caught any abuse from the engine bay side.

Or finally, a long shot - but is the rubber 90° elbow still attached to the spout? They're often missing, and it directs the stream away and down from the firewall instead of it possibly wicking back along the nipple and firewall.

Richard



It's absolutely humid enough where I'm at. About 2 hours south of you actually in San Antonio. Not today though, got a nice little "cold" front happening outside.

I'm thinking you're on to something about the drain nipple being cracked or rubbed through. My truck is a 300K ex-farm truck, so needless to say it's seen it's better days. If possible, I'll see about finding the correct diameter copper tube to slip over the outside of the existing tube.

The rubber elbow is long since gone. If there's even a remote possibility that having that little elbow will stop it from draining back inside the cab, I'll order a new one. Or find an aftermarket elbow off something else that'll work.

At this point I'm willing to try anything. It's a pretty significant leak. If it was just a few little drops here & there, I'd probably let it go. It's not a show truck after all, just a good ole work truck. But it's a significant leak. It soaks a rolled up micro fiber towel after about 15 minutes. So it's a steady stream that comes down.

But now that it's a nice day out, I'll try blowing some compressed air up the drain line first to see if it helps any at all.

Worst case scenario I'll just come up with something to dope up the inside of the truck with to stop the water from soaking the carpet. I'd rather fight to take off silicone in the future, than deal with a smelly mildew soaked carpet right now.

'91 Chevy C1500 SC LWB
'00 Chevy C2500 CC SWB


 
djackson210 
Poster
Posts: 86

Age: 37
Loc: San Antonio, Texas
Reg: 01-31-19
06-24-20 08:11 AM - Post#2797085    
    In response to djackson210

Well...I'll be damned if a section of 5/8" rubber hose doesn't fit right over that drain line. I'll be double dog damned if it didn't seem to solve the problem almost instantly.

I blew air up the drain line first, no help. I got a section of coat hanger & ran it around up in the drain line, no help.

I found a roll of 5/8" heater hose I had lying around, slipped it over the drain line from the engine bay side. Pushed it over the drain nipple as far as it would go, then started the truck & watched it drip. Let the truck run for 10-15 minutes, dripping the entire time. Not a drop of condensate on the inside of the truck!

So in summation for any folks who find this thread in the future. If you don't have the drain line elbow installed & your getting drips inside the cab. 5/8" rubber hose fits right over that drain line & stops it from dripping inside the cab.

I've still got a rolled up micro fiber towel shoved under there for the time being. I've got some errands to run today so I'll check the towel when I get back. If it's bone dry (as I suspect it will be) I'll report back with a 100% guarantee that this solved my particular problem. And it just might solve yours too.



'91 Chevy C1500 SC LWB
'00 Chevy C2500 CC SWB


Edited by djackson210 on 06-24-20 08:12 AM. Reason for edit: No reason given.

 
someotherguy 
Senior Moderator
Posts: 29170
someotherguy
Age: 50
Loc: Texas
Reg: 08-01-03
06-24-20 08:20 AM - Post#2797087    
    In response to djackson210

I sure hope the fix was that simple! That elbow is there from the factory for a reason, we don't always understand why engineers do the things they do (and they're not always right) but again, if that's the fix, then it's a win!

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
rockfangd 
"7th Year" Gold Supporting Member
Posts: 2926
rockfangd
Age: 34
Loc: Utica ny
Reg: 04-13-10
06-24-20 01:54 PM - Post#2797107    
    In response to someotherguy

As soon as you said the elbow was missing you nailed it.
The elbow keeps the air stream from being pushed through the drain tube slowing the flow.
I had issues with one of my Cadillacs that had the same problem.

Old School GM fan FOREVER


 
someotherguy 
Senior Moderator
Posts: 29170
someotherguy
Age: 50
Loc: Texas
Reg: 08-01-03
06-24-20 02:28 PM - Post#2797111    
    In response to rockfangd

  • rockfangd Said:
As soon as you said the elbow was missing you nailed it.
The elbow keeps the air stream from being pushed through the drain tube slowing the flow.
I had issues with one of my Cadillacs that had the same problem.


The only reason I called it a "long shot" is because here in SE TX where it's practically rainforest humidity even on sunny days, our A/C's drip water inside on a vehicle that has nothing wrong with it.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
wagonman100 
Super Senior Member
Posts: 14534
wagonman100
Loc: Baltimore, MD
Reg: 11-27-04
06-24-20 03:16 PM - Post#2797117    
    In response to someotherguy

Glad you found the problem. I hope that easy, free fix settles it for you.

Jay
Friends don’t let friends drive Fords.

1999 Silverado Z71 4X4 extra-cab short bed
1983 Malibu Fauxmad - tubbed
1978 El Camino Kustomized
1972 Monte Carlo
1957 210 handyman wagon
1957 Nomad sport wagon
1957 Cameo Carrier


 
djackson210 
Poster
Posts: 86

Age: 37
Loc: San Antonio, Texas
Reg: 01-31-19
06-25-20 10:50 AM - Post#2797167    
    In response to wagonman100

So, the tube solved 90-95% of the drip!

After about 2-3 hours of running around, even about 20 minutes stuck in traffic the micro fiber towel had a minimal amount of moisture to it. Not bone dry, but nothing like it was.

The last thing I'm going to do is take the tube off, put a little bit of silicone around the drain tube then slide the hose back on & see how that goes.

Thanks for all the help/info fellas. Much appreciated!

'91 Chevy C1500 SC LWB
'00 Chevy C2500 CC SWB


 
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