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Turn of AC before stopping at end of day

Hey, you guys, and the guy in Phoenix, are missing the point about why to turn off the AC before engine…it is to evaporate the condensate in the interior air handling system so as to dry it out and prevent mold and mildew in the evaporator and duct work area!!!
My wife does not like this either, but, it would be very difficult to clean out and kill a moldy mess in the evaporator and duct work.
part of this is also running the fan on a high setting for several minutes or more after killing the A/C compressor to blow things dry!
What do the rest of you think?
Spokane, WA

I’m with you on this one, Dave.
I won’t claim that I do this consistently, but whenever I remember to do so, I turn off the A/C compressor a few blocks before I get home, and run the vent fan for a few minutes in order to dry out the works.

That’s what I do too, turn the AC off a few blocks before I get home. It also keeps the garage floor dry. Haven’t had much luck instilling this habit in wife’s driving though-she parks outside, so far no mildew issues but I am not keeping my hopes high.

Make that 3 of us who shut off the AC early

I rarely, if ever, turned off th AC in my old 99 Civic, even in winter, and never had a problem with any mold/mildew smell in it when I sold it 2 years ago.

Is mold and mildew a big problem in the Spokane area? In my part of the country summertime humidity is a serious issue but when the temperature is usually above 90 most of the day moisture on the evaporator apparently evaporates quickly. It there is a problem with HVAC fungus it is usually in the fall and causes the musty odor on initial operation of the heater each morning. What indications are apparent for the concern to shut off the AC and blow the evaporator dry prior to shutting off the engine? What kind of moldy mess is there? How do you clean it?

Four – that is, when I remember.

I’ve never done this and never had a problem in any of our cars.

I’ve had A/C since '66 and never practiced the above senerio, and haven’t had a problem, that I know of. Never read about it in the owner’s manual either.

Whew, smells bad sometimes,great idea guys-never occured to me to do this,imagine that this fakes people out about leakey heater cores at times-kevin

Never done it before…guess this old dog learned a new one. But being an old dog, I’ll probably forget.

I’ve never done this myself, though I have heard of people doing it for various reasons. I’ve never had a problem though.

Spokane is kind of dry so I don’t think AC mold is a problem.

It might help a little in humid areas, but you’d have to really leave the fan on for quite some time to dry out all the water in the evaporator case. The air in the vents should already be dry with the AC on. You are likely adding humidity to them running the fan with the AC off.

And in Phoenix, I can’t imagine residual wetness being a real problem with the climate they have…

I do it partly to acclimate to the outside so it’s not such a shock when I get out of the car.
Also I’m such a cheapskate I hate to leave any unused “coolness” in the evaporator box.

It’s not so much a problem on newer cars because they have cabin filters. But older cars, which don’t, suck in dust and plant matter through the vents. That gets deposited on the evaporator coils, which as you know get wet. Wet dirt and biomatter is a breeding ground for things that can make the air smell unpleasant.

This is one of those good ideas I’ve never done, and never noticed a problem.

I do it mainly because when I get in the truck tomorrow I don’t want all this stuff ON all at once .
A different day… a different set of circumstances.
I turn off the radio, a/c, wipers, lights, and put up the windows.

Heck at this altitude you can park at the end of today having run the A/C…
And need heater in the a.m…( 28 degrees this morning 3/27 )


It’s not only at your altitude.
A couple of days ago, we had temps in the mid-80s in NJ.
Last night, it went down to 30 degrees!

I too am with you Dave. I very rarely use AC, but when I do I try to remember to shut it down a bit before my destination. Note that I said TRY to remember.