Odd Fog Up

[tlockhart]

I've had my vehicle for about 9 months now, no problems and love the thing to death. About 10k miles on it.

I drove it over a mountain pass for the first time yesterday, and it was also the first time the vehicle had been in temps below freezing. As I was coming up the pass, the temp dropped from 36 down to 26 degrees in a matter of one minute. The vehicle suddenly fogged up, every single window, and the Max Defrost could not handle it. It got to the point where I had to wipe away the condensation from the windshield, and then ultimately pull over and let the moisture leave. Every window was soaked and had water droplets dipping off of it.

It was a long drive, and I went over a few more mountain passes and never experienced the issue again.

Any idea what happened? Did the car have to adapt to being in the cold for the first time?

 

[R32driver]

That's pretty strange. Ours fogs up bad in the rear anytime you drive in the rain and have a few people back there but so did our '11 suburban. Seems you have to get the temp way up to where it's uncomfortable in the vehicle to get them cleared up. That's probably my only "real" complaint about these vehicles as it presents a safety hazard

 

[Joseph Garcia]

When your truck fogged up, were the climate controls on fresh air or recirculate air?

 

[Hotwifes21Tahoe]

This happened to our 21 RST Tahoe. It was last winter after a cold weekend. Max defrost, recirc., tried it all and could barely see out the windshield. All other windows completely fogged over to the point of water dripping down them. Took it in to the dealer. There is a drain for the evaporator that was plugged on ours. The foam gasket had fallen out and clogged the drain for the AC evaporator.

 

[tlockhart]

This happened to our 21 RST Tahoe. It was last winter after a cold weekend. Max defrost, recirc., tried it all and could barely see out the windshield. All other windows completely fogged over to the point of water dripping down them. Took it in to the dealer. There is a drain for the evaporator that was plugged on ours. The foam gasket had fallen out and clogged the drain for the AC evaporator.

Thank you! This sounds like exactly what happened with mine. I will take it in.

 

[swathdiver]

When your truck fogged up, were the climate controls on fresh air or recirculate air?

This!! ^^^

Happens to me in Florida all the time. I keep it on Recirculate all the time until this happens.

Owner's manual talks about it.

 

[tlockhart]

When your truck fogged up, were the climate controls on fresh air or recirculate air?

It was on fresh air, I leave it there pretty much 100% of the time.

 

[avalonandl]

You hit a dew point probably. I have seen fog litterally form in front of me when the temp drops and the misture has nowhere to go....

 

[G-Frog]

This is fairly common in more northern climates in the fall and spring. It happens with the inside temperature is warm and humidity is high. When you drive into a cold area such as a sheltered valley or high altitude where the air temperature suddenly drops by a lot, the windows will suddenly get cold. This caused the moist inside air to condensate on the inside of the windshield. This happens so quickly that the car's HVAC can't keep up. It is very annoying and can be dangerous in some cases.

Sometimes the opposite happens during summer when you have AC inside your cold vehicle and drive into an area of warm and humid air. Condensation forms on the outside of the Windows. Particularly at the vent outlets.

Just a note: recirculating the air, whether inside a vehicle or a home, will increase the humidity level. Warm moist air will condensate on cold windows.