Think you turned off your Air Conditioner?

[Paintor]

I read a few posts on the internet where people are having premature failure of their Air Conditioning Compressor on newer GM trucks and think I found the reason.

 

With your truck running, turn off air conditioning but leave blower blowing set on defrost to defrost your windshield. Pop the hood and notice your Air Conditioning compressor is engaged?

 

But .....you have the Air Conditioner turned off! Think GM has the computer do this to remove moisture from the air to defrost the windshield quicker....but....what if it is below freezing and there is no moisture in the air?

Refrigerant in air conditioning will undermine the oil lubrication in the compressor when it is below freezing outside.....killing it. So I think we need to physically unplug our Air Conditioning compressor in winter correct? To keep it from killing itself?

 

Any thoughts on this? 

[2017SierraSLT]

Manufacturers have been doing this for a long time. The compressor is engaged in defrost for two reasons. One to blow dry air onto the windshield, and two, to exercise the compressor. I have had several vehicles that are daily driven in the cold winter months, and never lost a compressor.

[Paintor]

5 minutes ago, 2013sierrasle said:

Manufacturers have been doing this for a long time. The compressor is engaged in defrost for two reasons. One to blow dry air onto the windshield, and two, to exercise the compressor. I have had several vehicles that are daily driven in the cold winter months, and never lost a compressor.

Not with the new refrigerant. R-1234yf

[2017SierraSLT]

We will find out then. I really doubt there will be any issues...

[sourdough44]

 I like my A/C compressor off as much as possible. Yes, they seem to turn on now anytime 'defrost' is on.

  My reason for doing so is to reduce moisture in the system and possibly lower some 'drag' on the engine. I do get ribbing from other family drivers at times. I also agree, some of my reasoning may harken back to older systems and not apply as much today.

  I never did like the idea of shutting a vehicle off with the A/C system on. I realize many people do it, just not my thing.

[Orlando8]

Nothing new, its been going on for many , many years . Not just GM

[MikeNH]

14 hours ago, sourdough44 said:

 I like my A/C compressor off as much as possible. Yes, they seem to turn on now anytime 'defrost' is on.

  My reason for doing so is to reduce moisture in the system and possibly lower some 'drag' on the engine. I do get ribbing from other family drivers at times. I also agree, some of my reasoning may harken back to older systems and not apply as much today.

  I never did like the idea of shutting a vehicle off with the A/C system on. I realize many people do it, just not my thing.

Reduce moisture where? Air conditioning systems can't have moisture internally- water doesn't compress and it would destroy the compressor. As for drag, running with your windows open on the highway causes more drag on a modern vehicle than AC does I'd bet given how much time and money they spend on optimizing aerodynamics. Compressors will also cut out at full throttle too so it is't like you're leaving power on the table. 

 

As for turning off the AC with the engine, it won't make any difference. You turn off the AC with the engine running, the clutch releases and pressures internally stabilize. Same thing if you just turn the engine off. In times past, I could see AC being left on being a drag while starting the engine but computers are smart enough now not to lock the compressor clutch while the engine cranks. 

[sourdough44]

 I remember back a ways, when the A/C was on the engine would go to a slightly higher RPM, noticeable at idle in park. In this instance, the engine had to work harder to run the air compressor.

 

  Also, one sees how the a/c drain tube allows condensation/water to drain after & while using the AC. This is even evident after parking & the vehicle is shut off. I'm not talking the touted comparisons between A/C use or windows down on gas mileage. The Windows will be up in my scenario. Even though there is a drain tube, the less moisture the better.

 

  Back in the day I ran some equipment where standard procedure was to increase cabin temp before shutdown to reduce moisture. Right or wrong, some of this has carried over to my vehicle operation.