Windows keep fogging up

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Arctic_Sierra

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Just bought a new 2010 Sierra and all the windows keep fogging up.

I don't smell anything so i'm assuming that I don't have a heater core leak.

I was wondering if anybody else has had this issue and if so what did you do to fix the issue. I don't want to bring my truck back to the dealer for my windows fogging up and finding out it was something that I did or didn't do. Just to let everyone know I live in Yellowknife and the tempature is around -6, not sure if that makes a diffrence.
 
Same problem

I have the exact same problem,,,,living in New Brunswick...should I call GM and ask?
 
Arctic_Sierra said:
Just bought a new 2010 Sierra and all the windows keep fogging up.

I don't smell anything so i'm assuming that I don't have a heater core leak.

I was wondering if anybody else has had this issue and if so what did you do to fix the issue. I don't want to bring my truck back to the dealer for my windows fogging up and finding out it was something that I did or didn't do. Just to let everyone know I live in Yellowknife and the tempature is around -6, not sure if that makes a diffrence.
Click to expand...

If I am not mistaken, the ac compressor disables itself below 4*C or 40*F. I think I read it in the manual, and the AC compressor get used to remove the humidity from the cabin when the climate control is used as a defroster.

My gut feeling is that it requires a new PCM update but i'm unsure if GM has an update yet. Check with the dealer and see if there is a update to the defroster a/c compressor cut off temperature. ;)

Keep us posted. ;)
 
windows fogging up

I just bought a new 2010 Sierra Crew cab diesel and I have the same problem, i took it in because it is becoming a safety issue, I live in Kamloops and it has gotten so bad at times with 4 of us in the truck to where I have to pull over and wipe th windows down. I took it in yesterday for teh supposed update flash , but it is still the same. Today i had to travel to Vernon approx 1 hr away and teh only way to stop the fogging was to drive with a window cracked open. This tells me thet the air circulation is poor and needs to be modified. i am going back in tomorrow to discuss. I didnt spend $50K on a new truck to drive around in -20 with my window cracked open so I can see.....I will keep you posted
 
I have a 2010 Sierra 2500HD SLE diesel and I have the same issue, and to be honest, I'm a little pissed off about it. I too did not spend $50k so I could drive around with fogged up windows like I don't have A/C. I have never had this issue with any other A/C equipped vehicle I have ever owned until this one. My owner's manual states the A/C is disabled below 0degC/freezing, who's bright idea was that? Just about every other vehicle ever designed or made uses the A/C to dry the air on the defrost setting... If the A/C doesn't work below freezing what's the point in having it work with defrost?? Last night I had it on full hot, full defrost, fresh air, full fan speed... and the windows were still fogging to the point I could barely see my side mirrors.

Other than that, I love this truck... and this is my first post on this forum, so sorry for the window fog rant. Anyone have any luck getting this corrected at a dealer? It seems to me it should be a simple software/programming correction...
 
In the ole days when the windows would fog up it was usually because the heater core was leaking which was a common thing. Never heard of it happening in today's vehicles.

Is there are movement of air coming from the defrosters? Maybe something is disconnected etc.

No problems with my 2010 SLT E. cab but one thing I have noticed is the plastics gassing are leaving a film on my inside ws. Cleaned it 3x in 7 months, maybe that's your problem?
 
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I have a 2010 Sierra 2500 quad cab and major fogging issues! I live in BC so thought the problem would cease on a recent trip to Saskatchewan....wrong....instead of fogging it was frost covered windows regardless of fan/temperature settings.
Dealership had triggered the "after-blow" but that didn't help.
Interestingly enough, on the last leg of the return trip from Saskatchewan I had water dripping from the dome lights in both the front seat and rear seat dome light covers...I'll update when I've had that looked into.
 
i had the same problem. I took it to my local dealer, they stated that they fixed it but that night to it for a drive the same thing happend again. Call the dealer and they came and picked it up again this time they seem to have fixed the problem. There is a temp fix they cam do it involves not using your recycle setting on your HVAC system just the Vent setting. They have to switch it over to vent, There is a panle in the back of your glove box where they switch it over to vent. There is a mechanics letter on it. Good luck they sure don't make them like they used too
 
Thanks Canadianhunter....my dealership just got that service bulletin and it's being done on my truck this weekend. Glad to hear it sounds like it works!
 
So has anyone been successful in getting this fixed? It's driving me nuts... The way I see it, the a/c should not be inhibited at ambient temps below freezing... who in their right mind would design this truck like that?
 
I have the same issue, brand new Sierra regular cab, manual heater control. Water coming out the dome light. Dealer seemed to unplug something behind glove box? Is there a TSB or any more specifis on this?
 
I opened up and tipped down my glovebox door, fiddled with the hvac controls until the recirc door closed off to the inside (fresh air position) and then unplugged the recirc door motor. Hopefully this helps because I discovered there is a TSB for this but no repair yet:

Subject: Excessive Cabin Moisture/Reduced Window Clearing
Models:
2010-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2010-2011 GMC Sierra, Yukon, Yukon XL
With RPO C67 or CJ3
Manual Hvac System
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
CONDITION/CONCERN:
In rare cases, some customers may comment of excessive cabin moisture or difficulty keeping the
windows clear in low ambient temperatures.
RECOMMENDATION/INSTRUCTIONS:
If normal diagnostics do not lead to a correction, inspect the HVAC recirculation door by lowering the
glove box. The door should be in the "Fresh Air" position, which closes off the recirculation opening
behind the glove box when the HVAC controls are in the floor to defrost position. If not, then follow
the procedure below:
1. Turn the vehicle ON.
2. Set the HVAC controls to a Vent/Panel position.
3. Press the Recirculation button on the control head.
4. Move the HVAC controls back to a Floor / Defrost position
5. Verify the Recirculation door has moved to the Fresh Air position by visual inspection.
6. Return the vehicle back to the owner and instruction them NOT to use the recirculation button and
that Engineering is working on a software update.
7. If the vehicle returns with this concern and the recirculation door is again in the recirculation
position then Contact GM Technical Assistance.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition
exhibited is resolved without completing every step, the remaining steps do not need to be
performed.
 
So I ended up unplugging my recirc door motor after getting it to close to the fresh air position. This after I found there is a TSB for it but no fix as of yet:

Subject: Excessive Cabin Moisture/Reduced Window Clearing
Models:
2010-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2010-2011 GMC Sierra, Yukon, Yukon XL
With RPO C67 or CJ3
Manual Hvac System
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
CONDITION/CONCERN:
In rare cases, some customers may comment of excessive cabin moisture or difficulty keeping the
windows clear in low ambient temperatures.
RECOMMENDATION/INSTRUCTIONS:
If normal diagnostics do not lead to a correction, inspect the HVAC recirculation door by lowering the
glove box. The door should be in the "Fresh Air" position, which closes off the recirculation opening
behind the glove box when the HVAC controls are in the floor to defrost position. If not, then follow
the procedure below:
1. Turn the vehicle ON.
2. Set the HVAC controls to a Vent/Panel position.
3. Press the Recirculation button on the control head.
4. Move the HVAC controls back to a Floor / Defrost position
5. Verify the Recirculation door has moved to the Fresh Air position by visual inspection.
6. Return the vehicle back to the owner and instruction them NOT to use the recirculation button and
that Engineering is working on a software update.
7. If the vehicle returns with this concern and the recirculation door is again in the recirculation
position then Contact GM Technical Assistance.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition
exhibited is resolved without completing every step, the remaining steps do not need to be
performed.
 
Just got back from the dealership, I was told that mine was the second one they fixed since GM came out with a software recalibration of the HVAC. They said the other person has had no trouble since the fix, so I'm hoping that is the end of my cab fogging up.

When I went in I handed them this and they new all about it.


Subject: Excessive Cabin Moisture/Reduced Window Clearing
Models:
2010-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2010-2011 GMC Sierra, Yukon, Yukon XL
With RPO C67 or CJ3
Manual Hvac System
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
CONDITION/CONCERN:
In rare cases, some customers may comment of excessive cabin moisture or difficulty keeping the
windows clear in low ambient temperatures.
RECOMMENDATION/INSTRUCTIONS:
If normal diagnostics do not lead to a correction, inspect the HVAC recirculation door by lowering the
glove box. The door should be in the "Fresh Air" position, which closes off the recirculation opening
behind the glove box when the HVAC controls are in the floor to defrost position. If not, then follow
the procedure below:
1. Turn the vehicle ON.
2. Set the HVAC controls to a Vent/Panel position.
3. Press the Recirculation button on the control head.
4. Move the HVAC controls back to a Floor / Defrost position
5. Verify the Recirculation door has moved to the Fresh Air position by visual inspection.
6. Return the vehicle back to the owner and instruction them NOT to use the recirculation button and
that Engineering is working on a software update.
7. If the vehicle returns with this concern and the recirculation door is again in the recirculation
position then Contact GM Technical Assistance.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition
exhibited is resolved without completing every step, the remaining steps do not need to be
performed.
*****************************************************************
 
watsonshort said:
Thanks. had mine in a week ago for software fix...seems good now.
Click to expand...

Let me know how it goes. I have an '11 Sierra 2500 CC Duramax, and it is really bad when it's cold... Fog and frost. I checked my recirc door and it seems to operate correctly. Taking it to my dealer next week.

Can you guys with the condensation problem confirm if you have a diesel or not? I have a hunch this problem is not happeneing to the newer gas engines... Just the diesels.

If it's not the recirc door and the truck is pulling fresh air only, then I'd like to know where the moisture is coming from... Especially when it is -20 and low humidity outside.
 
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Diesel engines are notorious for being cold blooded, get a radiator cover (GM option) so the engine warms up.

V10 Cover, 1-piece, covers radiator grille and front bumper openings for
diesel engines in winter weather
1 - Requires (LML) or (LGH) Duramax 6.6L Turbo Diesel V8 engine and is
required on orders with "Ship To" locations within the following states:
Maine, New Hampshire, Vermont, Minnesota, North Dakota, South Dakota,
Montana, Alaska, Idaho, Wisconsin, Wyoming, Michigan, Colorado and
New York.




There is also this Service Info



2010-2011 Avalanche, Sierra, Silverado, Suburban, Tahoe, Yukon, Yukon Denali, Yukon XL, Yukon XL Denali

-- Excessive cabin moisture/reduced window clearing, non responsive HVAC control

DO
Reprogram HVAC control module

DON'T DO THIS
Replace actuators or HVAC module


11-01-38-001B
 
Last edited:
Z15 said:
Diesel engines are notorious for being cold blooded, get a radiator cover (GM option) so the engine warms up.

There is also this Service Info



2010-2011 Avalanche, Sierra, Silverado, Suburban, Tahoe, Yukon, Yukon Denali, Yukon XL, Yukon XL Denali

-- Excessive cabin moisture/reduced window clearing, non responsive HVAC control

DO
Reprogram HVAC control module

DON'T Do
Replace actuators or HVAC module


11-01-38-001B
Click to expand...

Thanks for the TSB info Z15.
My HVAC system seems to be functioning properly... at least as far as the recirc door is concerned. I followed that TSB test procedure yesterday, and my recirc door opened and closed as it should. Maybe it malfunctions randomly. I will check it the next time I take the truck for a longer drive and the fogging occurs. It's pretty easy to check, since the door is clearly visible behind the glove box. (no tools required)

My Duramax gets up to full operating temp (100C/212F), albeit slower than my 5.3 gas did. And it cools down quicker when parked. My HVAC pumps plenty of hot air. So much that I can't stand the heat, but still have fogged windows. Even after driving for an hour or more on the highway, windows still fogged. Rolling the windows down helps, but it noisy and sucks at -20 C!

The strange thing is, heating up outside air raises its moisture capacity, which lowers relative humidity and should increase evaporation rates from moist surfaces (the windows), regardless of AC function. In other words, the heat should do the job, as long as the air is fresh. I am getting lots of heat. And it seems I am getting fresh air (recirc door remains closed). Hmmm.
 
my tk had this same problem all the time 2011 1500 sierra 4x4 5.3 6 speed.

Took it back and was fixed on the frist try no more problems so those of you with problems take them back becaues GM know about the problem. Also if GM can't fix it there is always the lemon law.
 
The only thing you may want to add is that when the conditioned air hits the cab glass it looses the ability to hold moisture.

The strange thing is, heating up outside air raises its moisture capacity, which lowers relative humidity and should increase evaporation rates from moist surfaces (the windows), regardless of AC function.

The 2 problems I've seen resembling your situation; 1) wet carpet ,water leaking into cab 2) hood not sealing at cowling area allowing warm, moist engine air to be sucked into cab. I haven't read the whole thread but you've probably checked to see that the evaporator coil drain is clear.
 
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