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FIX: Excessive Moisture/Condensation/Frost on Windows

76620 Views 53 Replies 24 Participants Last post by  Xnitro67
For some time now there have been many Cruze owners posting about excess moisture inside their Cruze, leading to foggy or frosted up windows that compromise outward visibility. My car was no different and I assumed, as most did, that it was somehow related to the small engine not putting out a lot of heat.

A couple weeks ago my car got to the point where all four of my windows were frozen shut (from the inside!) and the rear window was frosted over so bad that even using the rear defroster wouldn't clear it. The weather was cold and humid, yes, but I hardly ever have other people in my car and started wondering about how much more ridiculous it would be if I regularly traveled with several people in the car... it does have five seats, after all.

The evening of Friday January 16th was particularly COLD out, with temps hovering around -20C (-4F) and the sky was nice and clear; relatively low humidity. I decided to take my car out for a blast on the highway, get it heated up good and hot, and see if I could clear the windows.

A half hour on the highway with the heat blasting and the rear defroster cooking away, my windows refused to thaw. This could not be normal...

Fueled by some information I'd read in Colt45's thread regarding re-circulation and humidity, as well as member Robby's observation that the re-circulation flaps can be observed operating behind the glove box, I decided to pull into a gas station and have a look. Lo and behold my re-circulation flaps were not operating properly! They were out of sync with the commands from the HVAC controls, and both the fresh air flap and re-circulation flap were closed when in the Fresh Air (FA) mode. When I switched to the re-circulation (RC) mode, the fresh air flap opened. Here's a video I shot demonstrating the condition:

What I forgot to mention in that video is that when both flaps were closed (in FA mode), the fan was fighting to draw air through whatever gaps exist between the flaps and the housing, and since the gaps are much larger on the RC flap that's where most of the air was coming from... inside the car. Once the flap orientation was corrected I experienced a HUGE increase in airflow through the vents from fan speed 2-up (my car is a '12 with the 4 speed fan control).

Here's a video demonstrating the correct operation of the flaps as well as how to get them in sync with the HVAC controls:

This is extremely easy to check. If you have moisture issues and are not able to check this yourself, please get someone to check this for you. If your car is under warranty this will be your local dealer. Here's a How-To on cabin air filter replacement for those interested in looking at this themselves:

That frigid Friday night, once I had my car operating properly and frost-free remarkably quickly, I decided to test out how well it would defrost. I drove the car with the windows down and heat off to cool the interior, then pulled into a parking lot, shut the car off and rolled up the windows, and proceeded to breathe until all the windows were frosted over completely (several minutes). I started the car and put the defroster on full hot, fan 2, and was SHOCKED at how quick it started defrosting (the engine was already warmed up). By the time I got a video rolling half the windshield was already defrosted:

I should have kept the camera a little more still, but towards the end of the video you can see the moisture coming off. The sides of the windshield don't defrost nearly as quick as the middle directly over the vent. Remember, it was really cold out when I shot this!

I also met up with a local member who was having issues with moisture in his Cruze. Member stuckoncanada has a Cruze Diesel with moisture issues, and when we had a look at his re-circulation flaps he had an issue completely different than what I did.

His car was frost-free the night we met up, and indeed his re-circ flaps were in the FA position when we had a look. His issue was with the re-circ actuator not moving the flaps far enough. The gear seen in the videos SHOULD move about 7-8 teeth when switching modes, but the gear in his car was only moving 3-4 teeth. Instead of going into RC mode it would go halfway and stop with both flaps partially open. I have to assume that something was up with his re-circulation system that was responsible for his moisture issues as well. He has since had his car fixed at the dealer (re-programmed the HVAC module) and will report back with whether his situation has improved.

So it seems there are two separate and mostly un-related issues with the Cruze, one being the well documented "slow to heat" syndrome (small/efficient engines making little waste heat), and the second being the potential to have re-circulation system issues. I have a strong feeling that there are MANY people with the second (re-circ) issue who don't realize it. I was that way, assuming based on forum talk that it was just a "characteristic" of the car, even in the summer on rainy days!

And finally the most important part. If you have moisture issues REPORT THEM! This is important even if you are able to fix the issue yourself or get it fixed at your dealer! The NHTSA can only track issues it knows about. If this is an issue with your car and it is remedied without a report, the NHTSA will have no record of it and will not track the issue, nor will they be able to warn GM of the issue's severity and or warn other owners that this issue exists and to have their car checked out if they experience these symptoms. This is a hazardous issue that can, in extreme cases, make the car unsafe to drive.

If you have moisture/condensation/frost issues with your US Cruze, please report it here:

File a Vehicle Safety Complaint | | NHTSA

If you are in Canada, here is the link to the Transport Canada Defect Complaint Form:

Defect Complaint Form

Please feel free to reference this post if someone contacts you looking for further information.

There are many complaints about moisture in the Cruze on this forum. I have no idea how widespread the issue really is... there are hundreds of thousands of these cars sold every year in North America. I certainly see lots of people driving a Cruze with no condensation so this is not what I would call a common issue. I don't want to blow it out of proportion but I DO want people to be aware of the issue and also know how to go about fixing it or having it fixed.

My car is FROST-FREE now! I hope this post helps others get that way too. :)


UPDATE: I forgot to mention a very basic but very important point in my thread:

You can't watch the recirculation flaps move if you're in defroster mode!

You have to have the vent selector set to anything but defroster mode to get the recirc flaps to move. The HVAC system will automatically go to the fresh air position and stay there if the defroster mode is selected, regardless of which recirc mode you've selected.
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I'd also like to point out that wet floormats will have an effect. If you get in with a bunch of snow on your feet and it melts and saturates your mats, the moisture will rise and cloud up your windows and eventually freeze if it's cold enough outside. This is one reason why I don't use the rubber floormats(or weathertechs) in the winter. All that snow melts and just leaves puddles of water on your floor after you turn your car off.
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