Does anyone know at what outside temperature the A/C compressor switches OFF in full "Auto" mode? Cannot find any info in OM. Thanks.

 

My thought: Never, which kinda sux. It's probably always on in order to remove humidity if it isn't actually cooling / heating the car.

That's just my guess, though. I haven't ever noticed it going totally off.

 

It does switch off the A/C compressor at a certain temperature. If the outside air is cool enough to cool the cabin than it will use the outside air.

 

I think it will depend on what the ambient temperature is. If there is a large differential between outside and inside, it might cut off the compressor, as would be encountered in winter months. However, at higher temps, there is still likely high enough humidity to make the un-conditioned, lower temperature air "unpleasant", so the compressor may be asked to do its thing.

There is a switch that checks for abnormally high pressures, and will cut off the compressor. And below a certain temp (not sure what it is), the compressor is not run to avoid damaging it.

That is why the best days to run the "air" to keep the system lubricated and the seals pliant in the winter is not a very cold day - do it when the temp is around freezing or higher, for 10 minutes, then switch to auto. This is likely suggested in the manual, although I did not read that part - it is just good practice, so i would do it anyway.

 

It cycles on and off all the time in full auto. It's hard to detect in this car, but sit at a stop light and you can hear/feel it in the vibration in the car. Outside the car you can really hear it cuz it jacks up the cooling fans.

Sure the higher the differential it's going to run longer until it gets the car to the desired temp, but then it will start cycling on and off.

And yes, it even runs in winter like RR said to remove moisture, even with the heat on full.

That's why it's called "climate" control, not heating and air conditioning.

 

Most AC compressors will not switch on below zero - even in defrost mode. The humidity has lowered to the point where it isn't necessary, and it may cause damage to some systems. Where the system is programmed to shut off is a different story. At +5 degrees, if you hit the defrost, likely the AC will kick in. Likely the system contains a humidity sensor (if it is a good system) that also has a lot to do with the AC coming on. That is, if you live in a humid area, the AC will work much harder.

Ed.

 

Thanks, guys. I will try to determine when the compressor is not cycling when colder temps set in. I can definitely feel it cycle "on"; the car sort of moves slightly if I'm stopped in traffic. I'm surprised to find that it would cycle "on" in such cold weather. In full Auto in the Saab, it cuts out at 34 F, and I thought THAT was strange!

 

I simply hit the ac button when I turn on the heat and the "ac off" indicator comes on. My AC seems to run every time I turn on the climate control even when the temperature is in the 20's. You can hit the AC button or say Air Condtioning off through voice command. I don't need my air dried anymore when the temperature is in the 20's.

 

My car is the same way. It always turns the AC on when I push Auto, I guess I havent tried it below 0 degrees though.

 

Typically it's 3degC or 37.5degF. However, the sensor that controls this is not your ambient sensor, it's inside the HVAC right after the evaporator core. This is the same sensor that cycles compressor to prevent the core from freezing (the humidity it removes from the air)

The reason I believe it is not ambient sensor related is because I believe the manual says something about running the vehicle in recirc at low temperatures to help defrost the windshield. The only way this can be executed without fogging up your windows is by running the compressor. Thus it can't be related to ambient.