[skyjumper]

Why does the AC come on when I start my car and its 38 degrees outside? Can I make it not?

[F36GC_NYC]

Originally Posted by skyjumper

Why does the AC come on when I start my car and its 38 degrees outside? Can I make it not?

make sure its off when you shut the car off.. unless u are having other issues.

mine is off when i start the car unless i shut the car off while it being on it will turn on automatically when i turn on the car.

[Gen13 F36]

Originally Posted by F36GC_NYC

make sure its off when you shut the car off.. unless u are having other issues.

mine is off when i start the car unless i shut the car off while it being on it will turn on automatically when i turn on the car.

+1

All car I drove does this...

You leave it on .... its stays on
You leave it off.... its stay off

So far I haven't drove one yet that's different

[Billfitz]

Leave it on Auto and forget about it. If it's colder in the car than the set temperature it won't cool it further, it will heat it. Just pretend that the lamp that lights up says 'Climate Control'.

[F36GC_NYC]

Originally Posted by Gen13 F36

+1

All car I drove does this...

You leave it on .... its stays on
You leave it off.... its stay off

So far I haven't drove one yet that's different

my friend with an x5 had what the OP is describing, everytime i got in his car even in the winter the damn ac would always come on. now i was never able to confirm if he turned off the ac before he shut off the car, i thought it was bmw thing, until i got my own and discovered it wasnt... lol

[F36GC_NYC]

Originally Posted by Billfitz

Leave it on Auto and forget about it. If it's colder in the car than the set temperature it won't cool it further, it will heat it. Just pretend that the lamp that lights up says 'Climate Control'.

doesnt it stress the motor/engine if you turn it on as soon as you start your car? i usually wait a few mins before i turn it on manually.

[Billfitz]

The only things that come on as soon as you start the car are the indicator light and fan. After the car determines the temperature inside the cabin it then engages the compressor if it requires cooling, or it goes into heating mode if it requires heating. Of course the heating doesn't happen until the coolant temperature comes up.

[F36GC_NYC]

Originally Posted by Billfitz

The only things that come on as soon as you start the car are the indicator light and fan. After the car determines the temperature inside the cabin it then engages the compressor if it requires cooling, or it goes into heating mode if it requires heating. Of course the heating doesn't happen until the coolant temperature comes up.

so then i would ask does the fan stress the engine, right after a startup?

[Billfitz]

No. The fan is powered by the alternator, which starts producing electricity immediately upon start up.

[IAmATeaf]

When he says fan he’s talking about the little piddly blower fan for the ventilation, with the engine already running this won’t stress anything. I always leave mine set to Auto all year round and just let it do it’s thing.

[Billfitz]

Even without the engine running it won't stress anything. That's why you can set the fan to come on at a given time to ventilate the cabin per the Parked Car Ventilation section in the Owner's Manual. It's that big book that the dealer gave you when you bought the car that you still haven't gotten around to looking at.

[CrumbyButter]

Typically set mine to auto when its warmer out. In winter I manually set the fan speed and temps, If it's humid (rare when its cold) then ill change back to auto, but Ive noticed the car will turn on the AC even if set to manual if the cabin humidity gets too high.

[Wgosma]

Originally Posted by F36GC_NYC

my drive with an x5 had what the OP is describing, everytime i got in his car even in the winter the damn ac would always come on. now i was never able to confirm if he turned off the ac before he shut off the car, i thought it was bmw thing, until i got my own and discovered it wasnt... lol

Many modern cars use "variable displacement compressors", some compressor designs have no clutch, they are essentially always 'engaged' with the cooling output being modulated by the compressors ability to vary it's internal volume.

My X3 has this type of compressor, I can't sense it engage/disengage when pressing a/c button on dash controls as it is always engaged.

Maybe F30 uses similar compressor?

[F36GC_NYC]

Originally Posted by Billfitz

Even without the engine running it won't stress anything. That's why you can set the fan to come on at a given time to ventilate the cabin per the Parked Car Ventilation section in the Owner's Manual. It's that big book that the dealer gave you when you bought the car that you still haven't gotten around to looking at.

..... no comment can i interest you in a beer?

[F36GC_NYC]

Originally Posted by Billfitz

No. The fan is powered by the alternator, which starts producing electricity immediately upon start up.

well you learn something new everyday.

i will now leave it on auto from now on

[AlpineX]

AC on 100%of the time to keep those seals lubricated.

[F36GC_NYC]

Originally Posted by AlpineX

AC on 100%of the time to keep those seals lubricated.

come again...

[Wires]

If the compressor does run, the seals can dry out, and then it will leak refrigerant.

For the record, the AC compressor cannot run at temperatures less than freezing, or the condenser freezes. There is no point in turning it on/off, just set it to auto and forget about it.

[AlpineX]

The refrigerant conditions the seals throughout the engine compartment and underdash.

[xpro]

the reason your AC comes on because your car is obviously fitted with humidity sensor. As soonest there is any bit of humidity, the AC runs regardless of your panel settings.
A one of those stupid BMW features

[rparnel1]

I've also noticed that the car will run the AC compressor, even with the compressor switched off), when in auto and the humidity is high or there is the slightest amount of window fogging. It switches itself back to a compressor off condition after a few minutes.

[Desertnate]

Originally Posted by xpro

the reason your AC comes on because your car is obviously fitted with humidity sensor. As soonest there is any bit of humidity, the AC runs regardless of your panel settings.
A one of those stupid BMW features

Living in an area with high humidity all year round (unless temps are well below freezing), I appreciate the feature.

I've previously owned cars without climate control and always had to turn the A/C on in the winter to keep the windows from fogging up when carrying passengers when the weather was rainy or really cold.