# Defrost not working ***Efficiently***



## au201 (May 18, 2013)

Before I start, I'll say I know this issue has been discussed ad nausium, but I'd to get opinions on WHY our defrost is not nearly as effective as other vehicles. 
I'll preface this by saying I HAVE checked my recirculating door and it is working as designed. When the door is set to outside air, it pulls outside air. 
The other day it was raining and around 48 degrees. I had been volunteering in the rain all day, and was not soaked, but damp. As I was driving home, I had the heat on my feet and I noticed the windshield starting to fog. So I just changed the HVAC to defrost. There was little fogging so I left the fan speed on 2 (4 speed fan) thinking that should be enough. Shortly the fog was not disappearing, in fact, it was getting worse. I checked to make sure the air was on outside air and turned the fan up to 3. The fog kept getting worse. At this point, ONLY 80% of the windshield was clear, the side windows were completely fogged so you could not see out of them. (The rear window defroster works perfectly). I cranked the fan up to 4 and it clears a small section on the driver and passenger window; just enough to see out of. It stayed like that for the rest of my drive with the fan speed on full. I then got out of the car and it sat idling with the defrost kicking for 15 minutes. When I got back in the windows were almost clear, but quickly began fogging up again. They are almost impossible to keep clear when it is ranting and chilly. This happens even when j am dry. 

Does anyone have any idea why the Cruze defrost system is so bad?? Is my car doing what it's supposed to? It seems everyone has this problem, so I'd assume it's working as designed. But why is it designed to not work? My girlfriend has a Buick Verano and with the climate set on auto the windows stay completely clear no matter how much moisture is inside or how hot the interior is. The Verano is about the same size as the Cruze...in other cars when I turn defrost on it clears all fog within seconds even on low fan speeds. Any ideas why the Cruze can't do that? It was above the temp cutoff for the compressor...so it should've been drying the air. I even hit the A/C button to turn it on (I know it's on with defrost) and it didn't make a difference. 

Interested to hear ideas or other experiences. It's worth noting that I never had the inside frost issue where my windows frosted up on the inside in the winter. But it is kind of annoying to have to drive down the road with the fan blasting air any time it rains. Would changing my cabin air filter help? I should be doing that soon anyways. 


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## Aussie (Sep 16, 2012)

I have automatic air conditioning in my Cruze and never have any fogging of the windows. In other cars I have found the problem you describe was easily fixed by using the A/C with the heater and all the windows would clear up quite quickly. The A/C removes the moisture from the air and that is what causes the fogging. I also put the controls to recirculate, otherwise you are just bringing more moist air into the car.


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## NickD (Dec 10, 2011)

On my 2012 2LT the difference between blower speeds 3 and 4 is going from a breeze to a hurricane. Come to think about it, I complained about this to my dealer three years okay, requires a firmware change. He was going to get right back to me, this was three years ago, never did, just had to learn to live with it. 

Can't be in recir mode, just recirculating your own breathe, major cause of interior fog. Ha, my son calls me, dad, my furnace is constantly cycling, first question I ask him, when was the last time you replaced your air filter. Sure enough, its jammed, insufficient air flow, kicks out the many thermal breakers.

Same problem with the Cruze with that cabin filter, but just drastically cuts down on air flow. Don't get me wrong, I love that cabin filter, keeps all that crap out of the MVAC system, but does have to be replaced, depending on where you live.

Still a dirty world out there.


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## jblackburn (Apr 14, 2012)

Weird. When I switch to straight defrost mode, the windshield clears up within 10 seconds, sometimes before I hear the airflow even switch directly to the windshield. 

The floor/defrost mode works less well on low fan speeds. 

I'd say that maybe your evaporator drain isn't draining out - can you leave the AC running for 10-15 minutes and see if water is coming out under the car?

(Recirculate is the last thing you want on to keep moisture off the windows.)


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## spacedout (Dec 7, 2010)

Mine will defrost most of the time just fine then I was experiencing the exact same thing at random times. Hills and valleys are at the worst, finally installed vent visors so I can crack a window or 4 when raining, now I no longer have to deal with this. 

Before I got the vent visors, I have had times I start up a hill and enter fog half way up by the top ALL my windows are fogged over 97% with me attempting to keep the car on the road looking though the 3% that's defogged in the lower center windshield. Think the cruze HVAC is the worst of any car I have owned.


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## NickD (Dec 10, 2011)

Evaporator plugged drains, another age old problem, passenger side carpet would be soaking wet. Open it up and find a pile of mud plugging up that drain. Hopefully the cabin filter would cure this age old problem. 

Mold is still a problem if you don't switch off your compressor and switch the blower to high before you park it for the night. Augmented by placing the fins even closer together for a more compact evaporator.

AC was introduced production wise in about 1955, ha, darn near doubled the price of a Chevy, this was 60 years ago, but have yet to read in any owners manual the problems caused by mold build up. Still want to teach you this the hard way. All the intake air, whether recir or not has to go through the evaporator, if that plugs up with debris or mold, will have a problem. With mold, also a nasty odor.


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## JerTM (Dec 12, 2014)

My defrost issue was resolved with a fresh cabin air filter.


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## au201 (May 18, 2013)

Hmm. So defrost works fine for some of you? I wonder if my heater core is bad...I can't tell from the smell...what does a bad heater core smell like? My heat has a distinct smell but I wouldn't call it sweet. It just smells like hot air...if that makes sense. It seems like when I make the air cooler it defrosts better...I'll try changing the cabin air filter too...that needs to be done anyways. 30 miles here soon 

I will say I had the coolant topped off according to the recall 10k miles ago and I am still a tiny bit above the full line in the reservoir...I don't seem to be losing any. 


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## jblackburn (Apr 14, 2012)

> Hmm. So defrost works fine for some of you? I wonder if my heater core is bad...I can't tell from the smell...what does a bad heater core smell like?


Maple syrup. It's usually quite noticeable.

If it refuses to defog, that is entirely possible, and would not be unheard of for the Cruze either. There would be a hazy film on the inside of your windows as well.


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## au201 (May 18, 2013)

jblackburn said:


> Maple syrup. It's usually quite noticeable.
> 
> If it refuses to defog, that is entirely possible, and would not be unheard of for the Cruze either. There would be a hazy film on the inside of your windows as well.


Would this film stick around even when the windows are clear? Meaning I'd see it in direct sun? Because my windows are perfectly clear when not fogged. 

Also, it defrosts itself fine when I get out of the car and leave it on defrost. When I get back in, it doesn't fog up as bad again. I have weather tech floor liners, so it's not saturated carpets. 


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## jblackburn (Apr 14, 2012)

Yeah.

I might look into this if I were you:
http://www.cruzetalk.com/forum/25-s...sive-moisture-condensation-frost-windows.html


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## au201 (May 18, 2013)

jblackburn said:


> Yeah.
> 
> I might look into this if I were you:
> http://www.cruzetalk.com/forum/25-s...sive-moisture-condensation-frost-windows.html


I've checked my blend doors. They are working as designed...that's what's baffling me so much. Aha


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## ChevyGuy (Dec 13, 2014)

In order to pull water from the air, both the A/C and the heater have to run and be effective. People have complained about the weak heater on the Cruze. I wonder if the A/C was throttling back to match the ineffectiveness of the heater and so no dehumidifying was going on.

Since you say the outside was 48, I assume you wanted to warm the inside. How was the heater doing?


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## NickD (Dec 10, 2011)

Even at 50*F ambient, R-134a pressures drop to around 40 psi and are next to worthless for generating any cooling for defrost operation. Running the compressor only serves to burn it up a heck of a lot quicker. Then using woman's facial cream for a lubricant that is essentially worthless and really loses its lubrication properties. 

The moisture in the air drops significantly as the temperature decreases, so running the AC compressor has the major effect of wearing it out.

Not only this, that compressor neoprene seal gets rock hard and actually can cut into the compressor shaft causing leaks. Below 35*F the high side thermistor kills compressor operation. So between 35*F and below 70*F avoid defrost operation at all cost, because this cost is to me. Just crack open the window to keep the windshield fog free. Been doing this since day one and AC systems last a long time.

On older vehicles could defeat this operation, but dead meat on the Cruze, strictly firmware feeding the BCM for control and don't have the source code. So just crack open the window, not that cold anyway. After a few minutes with fresh air intake, heater takes care of keeping the windows fog free.


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