Disengage AC Before Shutting Off Engine?

[OK-944]

I’ve often wondered whether it might be advisable to shut off my AC a few minutes before I plan to stop driving and shut off my engine…but I’m really not sure why. Anybody?

Another thing…I usually make sure that my engine’s rpm’s are relatively low prior to turning the AC on - as I believe I’d read something somewhere that this puts less stress on the AC compressor than would be the case with high(ish) engine rpm’s. Make sense - or not?

[944 Ecology]

Sure, sound like prudent measures for longevity, much like avoiding jack rabbit starts, or locking up your wheels when braking, but we're probably talking in terms of hundredths of a percent improvement.

[originalowner]

Shouldn't really matter. The compressor cycles on and off numerous times while running at normal engine RPMs, so it won't make much difference in clutch longevity. The clutch is automatically disengaged while cranking the engine over, so no additional load while starting. The only reason I can see to turn it off is if your car has difficulty idling while the engine is warming up.

[v2rocket_aka944]

I've always heard you shut off the AC a few minutes before parking so that any condensation in the evaporator gets blown out, rather than leaving a cold puddle inside the car to mildew.

The engine doesn't care and the compressor doesn't really care about RPM...it's got a clutch of its own to bring it up to speed but the guts are made for high RPM.

[OK-944]

Makes sense to avoid mildew! (I hate mildew!)

...and good to know that the compressor has great guts!