A/C stays on



2009 Nissan Frontier. When the air flow knob is turned to windshield defrost and then turned back to regular air flow, the A/C stays on until the ignition is turned off. My service man at Nissan says this is normal. I don’t believe it.


How do you know the AC stays on?


Surely the a/c compressor stops cycling if you turn the blower control to ‘off’.
Or is it some cutting edge climate control system you can’t fully shut off?

Go to the dealer and check out another Frontier. See if it’s just yours.


If the car has a failure why would the Dealer not fix it and submit a claim?

Have you expressed your doubt to the service manager?


This is a feature built in to this vehicle to " keep moisture from accumulating, which could cause mold to grow " is what I was told. There is a way to disable this. You may want to check all the car forums out there. I remember seeing something about a switch up under the dashboard that you can reset. I wish I could help you more.


It is normal for the A/C to work on “defrost” but I think it should shut off when you go to heat or vent.


I believe Endorf may be right that some of the new systems do this. It prevents the musty smells by allowing the evaporator core to dry some, thus not becoming a good environment for spores. I’ve heard of this before too.