OT Auto Air Conditioner off or on

Anonymous-0 · Jun 24, 2009

I always leave my air conditioner on when shutting off the engine. A few days ago I had my car serviced at a quality repair shop and when i picked it up the air conditioner was off. Is this the proper procedure? Should I also do this?

440roadrunner · Jun 24, 2009

Frankly I don't think it makes two beans difference. I AM, however, in the habit of turning it off, opening the windows, and running the heat full blast for the last 2 minutes when coming home, especially if I know that the car will be parked for more than a day or two.

This helps heat up the evap and evaporate condensate which can eventually form mold, and smell.

Unlike the home/ commercial AC I used to service, most vehicles are nearly impossible to flush/ clean out the evaporators

Patsdeere · Jun 24, 2009

Maybe the guy driving it is cold blooded and couldn't stand it.

I leave mine on all the time except when I start the engine. My car is older and it is a lot of effort for it to try and start the engine and a/c at the same time.

lucas boy · Jun 24, 2009

At my brothers car dealership, gm teaches mechanics to turn everything off untill car is started. turn everything off right before you turn the engine off .i dont know why?? possibly surges of electricity during starting?? i dont know..

Mike (WA) · Jun 24, 2009

Fortunately, the decision is taken out of my hands by my '95 Lincoln Continental, with climate control. As long as it is in Automatic mode, I figure it can figure out what it wants to do, and I try not to interfere.

Major bummer when I discovered that Mr. Lincoln would not qualify for the Clunker money- Mileage is too good! Go figure! Needs to be 18 MPG to qualify- it gets about 19 in town, 26 on highway. I guess this is a tacit approval of my continuing to drive it, so will do so. 198,000 miles, has never used any oil between changes, even if I stretch them out a bit. Is it more comfortable than a Chev Aveo, or is it just my imagination?

ericlb · Jun 24, 2009

i always turn mine off, there is no real reason for one over the other, unless its just that time of year when you run the heater in the morning and the air conditioning in the afternoon, and like me you warm your engines up before putting a load on them, good engines last longer that way there may be sligtly more draw on the starter due to having to roll over the locked a/c compressor when the engine is first started, but ive never tested that

RobMD · Jun 24, 2009

Quite frankly, I DON'T like hot air blowing on me full blast when I start the car/truck after setting in the hot sun all day.

Thus, the air is always off before I turn the vehicle off.

Goose · Jun 24, 2009

Maybe the fella who was servicing it just didn't want the compressor running while he checked the trans fluid, etc. under the hood with the engine running.

440roadrunner · Jun 24, 2009

It COULD be argued that it's very hard on the ignition switch

cbop · Jun 24, 2009

Most ignition switchs disable power to non-essential systems when in the 'crank' position

Dick W. · Jun 24, 2009

The ac doesn't turn the compressor when the key is at the start position.

440roadrunner · Jun 24, 2009

(quoted from post at 18:48:39 06/24/09)
Most ignition switchs disable power to non-essential systems when in the 'crank' position

Yes, but when you turn from off, past on to crank, the switch has to "switch" whatever is turned on. If you have a bunch of junk turned on, like wipers, high blower, the teenagers overpowered stereo, AC (clutch) and I don't know what else, that will arc up the contacts all that much more.

Arcs once from off "to run"

Arcs again shutting off "run" "to crank"

Arcs once more "back to run"

Allan in NE · Jun 25, 2009

Doesn't make 6 eggs worth of difference. :>)

Allan

Leroy · Jun 25, 2009

I think most mecanicks turn either the heater or air off when checking a car because they do not want the sound of the blower to cover up any sound they might be listening for to determin if there is a problem that a bit of noise will aleart them to.

Bob Kerr · Jun 25, 2009

I shut mine off when stopping for one main reason. Right after starting the alternator is trying to replace the voltage and amps used by the starting motor. With the air on and starting the engine, the ac clutch uses a fair bit of current and it just makes the alternator pull harder trying to recharge the battery and run the compressor clutch and AC fan at the same time. Ever notice someone starting a car and hearing the belts squeal loudly? That is either the belt being loose or the alternator load is exceeding the belt capability.

Jon Hagen · Jun 25, 2009

Probibly makes little difference, as most cars cut off the accessory circuit during cranking, so blowers, AC compressor are not powered until you release the key back to the run position.
I suppose shutting things off would lessen the loading of AC compressor and alternator on the engine the instant it starts.

OT Auto Air Conditioner off or on

Anonymous-0

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440roadrunner

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Patsdeere

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lucas boy

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Mike (WA)

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ericlb

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RobMD

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Goose

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440roadrunner

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cbop

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Dick W.

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440roadrunner

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Allan in NE

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Leroy

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Bob Kerr

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Jon Hagen

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