AC will start on defrost position

[jivoinm]

I have 2003 Pontiac Grand Prix and the AC starts to blow cold when I switch to defrost position even the AC button is off. When I move the fan switch to blow in front the AC is disconected. What can it be?
Thanks,
Mircea

[SJAndrew]

It's wired this way. Cold air has less capacity to hold moisture - I think pretty much every car turn on the AC when you're in defrost.

[Scottydoggs]

yup a/c works when the defroster is turned on. and any heat setting it seems on my car.

this is why i pull the relay for the a/c compressor every winter. i see no reason for it to be running at all, and have no issues doing so.

[SJAndrew]

The only reason I like this 'feature' in the winter is it keeps the system lubed year round.

[jivoinm]

I haven't noticed this before, maybe because I can hear now better as car gets older when the compressor gets engaged Thanks for your replay.