Hello 5ers!

The weather in Phoenix AZ has finally cooled off to the point where outside temperature in the morning (around 58-60F) is cooler than the temperature set on the dash knobs (about 76F). When set on "Auto", though, the AC also seems to be on.

Does the system always run AC just to keep the air dry, even when you are trying to warm up the cabin? If so, I guess I can't really look forward to the annual "mileage improvement" that usually happens when I turn off the AC in my old vehicle...

Thanks, Jon.

 

I believe the AC stays on until the outside tempature falls below a certain termperature -- 40 or so. Having said that, you can turn off the AC manually by pressing the snow flake button in the middle of the console.

 

You can manually turn the compressor off (Snowflake symbol) whilst keeping the Auto button on - the system will do it's best to adjust to the desired temp without the compressor.

But imho, I would leave it on. I doubt you will get more than a 1-2mpg improvement, plus with the compressor on, the coolant is always circulating and since this stuff also as the lubricant for the system, it will stop valve seals from cracking and reduce the need for re-gassing the system.

The BMW system is also very clever, the system controls the humidity of the air in the cabin so that it doesn't get too dry - so I would say the compressor is on by degrees, rather than a simple on/off arrangement.

 

Most, if not all cars, cycle the A/C compressor briefly after every engine start to prevent this problem. There should be no problem in this area if you leave it off for long periods.

 

Hi Jon:

I am in Phoenix and haven't even thought about the issue. I did turn the climate control off this morning. One poster indicated that the compressor is on in degrees. And, that is right. There is no actual clutch for the compressor. So, having auto on might affect mileage and HP very little in the winter. Maybe others will provide more enlightenment. I know that my Z06 tries to leave the compressor on pretty much all the time when set to auto.

 

I am in Phoenix and haven't even thought about the issue. I did turn the climate control off this morning. One poster indicated that the compressor is on in degrees. And, that is right. There is no actual clutch for the compressor. So, having auto on might affect mileage and HP very little in the winter. Maybe others will provide more enlightenment. I know that my Z06 tries to leave the compressor on pretty much all the time when set to auto.
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If you turn off the AC the compressor do not work and it will give you better milage.

If you during the wintertime don't use the AC, you should anyany run it weekly for a while so that the parts would dry up.

Note also that the AC compressor will not necessarily start in temperatures below freezing. If you do not have a garage, you can take your car to a awrm parkinghouse etc. and then get it started.

I usually drive with the AC on also in the winter, beacause it drys up the car and so you will not have any problems with frosty windows.