So should A/C be turned off before car is shut down? Does it matter?

[Remobz]

Hey all,

Should the A/C be turned off just prior to the car being turned off?

In hot climates (like Arizona in summer time) should the A/C be left in the on position while the car is turned off to let vents "breath"?

So whats the deal with leaving the A/C on or off in hot climates?

 

[LTC8K6]

There's no reason at all to turn it off.

The car will "breathe" anyway. The car is not sealed up.

The compressor is not on during cranking, so it does not affect starting the car.

 

[JulesMaximus]

It doesn't matter at all.

 

[Spicedaddy]

I try to turn it off 2-3 minutes before I get to destination, but leave the fan working.

Prevents condensation in the system, so it doesn't smell like crap when you start it the next day.

 

[Remobz]

I noticed my owners manual for the mazda tribute says this....

"Under normal conditions, your vehicle’s climate control system should be
left in any position other than MAX A/C or OFF when the vehicle is
parked. This allows the vehicle to “breathe” through the outside air inlet
duct."

 

[Throckmorton]

I noticed my owners manual for the mazda tribute says this....

"Under normal conditions, your vehicle’s climate control system should be
left in any position other than MAX A/C or OFF when the vehicle is
parked. This allows the vehicle to “breathe” through the outside air inlet
duct."

Makes sense. A car is basically sealed when you have it on "max AC". This isn't 1960 when cars were made of cheesecloth. You can actually suffocate due to CO2 buildup if you sleep in a car with the windows closed.

I don't even use max AC, I like to keep fresh air coming in.

 

[LTC8K6]

Cars are never total recirc, iirc.

 

[tortillasoup]

Recirculation and A/C are two separate functions. You don't need the fan and or the A/C running, just keep it on fresh air intake for most of the time which is what I do anyway otherwise the car gets stuffy.

 

[Zenmervolt]

Recirculation and A/C are two separate functions.

This is technically true, but does not reflect how some systems are actually labeled.

Ford (along with some other makes, and definitely the OP's Ford-based Mazda Tribute) has a "Recirculate" setting that recirculates air with the A/C off, an "A/C" setting that runs the A/C with fresh air, and a "Max A/C" setting which runs the A/C with recirculation.

Many people do not know that "Max A/C" means they're on recirculate with the A/C compressor on.

In modern A/C systems (with electronically controlled blend doors instead of the old cable-operated setups and a microchip controlling fan speed instead of a resistor in the fan speed knob) the "Max A/C" generally also forces the fan to "High" and selects only the dash vents.

Leaving the selection on "Max A/C" could prevent the vents from breathing when the car sits and could allow mildew to form in the vents, but I have to admit that seems unlikely in practice.

ZV

 

[Doppel]

Never worried about it, never, ever will.

 

[Remobz]

This is technically true, but does not reflect how some systems are actually labeled.

Ford (along with some other makes, and definitely the OP's Ford-based Mazda Tribute) has a "Recirculate" setting that recirculates air with the A/C off, an "A/C" setting that runs the A/C with fresh air, and a "Max A/C" setting which runs the A/C with recirculation.

Many people do not know that "Max A/C" means they're on recirculate with the A/C compressor on.

In modern A/C systems (with electronically controlled blend doors instead of the old cable-operated setups and a microchip controlling fan speed instead of a resistor in the fan speed knob) the "Max A/C" generally also forces the fan to "High" and selects only the dash vents.

Leaving the selection on "Max A/C" could prevent the vents from breathing when the car sits and could allow mildew to form in the vents, but I have to admit that seems unlikely in practice.

ZV

Thank you for explaining this.

I live in a tropical climate (hot and humid) where people use car A/Cs a lot. I just bought a second hand 2003 mazda tribute and never bothered to read the whole manual. It is a good thing I did last week although I was not really sure how important those A/C settings were considering the type of climate I live in.

Trust me when I say bacteria thrives in this climate compared to you guys who live in winter climates.

From now on, I am leaving it at A/C setting when I have it parked in the hot sun.

 

[The Boston Dangler]

i was under the impression that for older cars AC was to be off during starting, and was not an issue for modern cars equipped with electronically controlled fans and clutches on the compressor.

 

[LTC8K6]

Have to be pretty darn old to have the compressor clutch on during cranking.

 

[Spec412]

Doesn't matter , cars with climate control stay engaged all the times

 

[LTC8K6]

Doesn't matter , cars with climate control stay engaged all the times

They are smart enough not to turn the compressor on until the engine is running.

 

[hanoverphist]

if it mattered, all those people here with remote start to get the car cooled down would have had issues by now i would think. i rarely run the ac in my cars, so they are generally in the off position all the time. my work truck gets left on all the time.