Fogging Up

halloweencats · January 17, 2011

2010 Sierra Crew Cab here , fogs up with every combination of HVAC controls. Ends up icing in from the inside, once parked and it gets a chance to cool down. I had a 2004 Sierra and never had any issues at all. Is there anything other than what you guys mentioned?

I'm having the exact same problem. I've had to scrape the frost off the inside of my windows as well as the outside. Have you found any solution for this issue?

tobypineo · January 17, 2011

Negative. Nothing has worked. Had a 300 mile trip with the family yesterday, ice on the inside the whole trip. Windshield is fine, but the side windows ice over. 5 of us in there, lots of humidity in our exhaled air, but I have never had this issue before.

My understanding is the that AC will remove moisture from the air, but this won't come under under 40 degrees F...not sure what to do. Dealer said "yeah, they all do that" when I brought it in for tires. I didn't push it, but will when I need to go in again for something.

PGDriver · January 17, 2011

Mine too, 5 of us in the truck - 25C outside but the truck was in a heated garage and it was clear when we left and slowly started to ice up inside.

Had the heater set to defrost and the fan speed to max with outside air. Will have to check with the service dept. and see what they say.

Sir Dan · January 17, 2011

One thing lots of people don't consider is that if there is lots of moisture on the floormats from snow or slush being tracked in, the windows will fog up quite a bit as the interior of the truck warms. Carpeted floormats are especially bad at retaining moisture. With all the snow we've had this year, I bet lots of folks are dealing with this.

nick3941sd · January 17, 2011

Ive had it happen to me tonight and once last winter. To me it seems to happen only happen on the colder days. Tonight on the ride into work it was -6F. It was clear when i left and out of no where all my windows fogged as i was driving. It was like a frost on the inside of the windows. I then changed the temp to cold on the selector and that cleared about half the windshield pretty quick. Not sure what causes it but to me I think its something to do with when the weather is pretty cold. And the selector was on full defrost.

Debo511 · January 17, 2011

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.

********************************************************************************

*******************************

ColoRocky · January 17, 2011

One trick I learned from a southerner while I lived in the great white north:

Lower your sunvisors... The defroster heated air will circulate and defrost/de-ice the windshield faster.

Ryan00TJ · January 18, 2011

Buddy at work was saying his was doing this and wondered if I had this problem. I've not yet experienced this.

SouthCo · January 18, 2011

I haven't had any problems with this, so don't let the dealer tell you that they all do it.

VIP502 · January 19, 2011

2011 Silverado WT fogs and ices up inside of windows whenever it gets below 32, which is all winter here in Central New York. No fix as of yet.

rob1231 · January 19, 2011

My truck would fog up all the time as soon as I got in, so I picked up some Rain-X de fogger (i think its called that) and it works AWESOME. Put a little bit of this liquid on a cloth or rag and wipe the inside of the window with it. You will very rarely use the defrost with this stuff.

EDIT:

http://www.canadiantire.ca/browse/product_...D=1295397929511

best 6 bucks you ever did spend.

Dale_K · January 19, 2011

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.

********************************************************************************

*******************************

I was just getting ready to start a thread about the fogging. The TSB might be correct for me. I have a 2010 work truck with manual HVAC controls and my truck fogs pretty badly. The funny thing is that I've never noticed a change in sound when I pushed the recirc button in hot weather trying to get the AC to work harder. Maybe it is already stuck in the closed position. I'm gong to check if I can figure out which way is closed vs. open.

Update... I just went outside and the door appears to be working. I can see it move and in my truck the recirc button seems to be deactivated in software whenever I'm in the floor heat mode. The button just flashes and the door is forward, which seems to be the way it moves for outside air. When I put it in knob all the way left to dash level discharge the recirc button works and the door behind the glovebox moves.

Trouble is I'm still getting the fogging and I think there might be some debris in the HVAC box holding moisture. My truck sits parked outside under a big pine tree and there's no screen to block small items like pine needles and pine stamen (sp). My GM car has a screen but not the truck - seems odd. Anyway, I'd like to inspect the HVAC box to see if there's anything in there. Is this easy to do?

trannybrad · January 20, 2011

I have a 2010 gmt 900 with just under 10k miles and its doing the exact same thing. Work as a gm tech and plan on taking the truck in to the dealer to have it checked out cause it can't be normal. Going to do a bulletin search tomorrow for this at work.

jklawn&Plow · January 20, 2011

My new reg cab is doing this. Its worse as I add 1 or 2 more people to it. I have outside air on but must crack window ~1/2" then it goes away. Mainly just on side windows with defroster blasting front and rear defroster taking care of back. Maybe after a warm summer its history for next year.

jtstacy77 · January 20, 2011

I had the same problem with a brand new 07 yukon, windows fogged up on the way home from the dealership. The heater core was leaking and had to be replaced at 300 miles.