I've always wondered, should you shut your AC off first before shutting your car off? I always do whenever I drive someone's car (my AC doesn't work) but I never see anyone else do it. Am I just being nitpicky?
Turn A/C off first before shutting off engine?
- Thread starter 55Test
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I am in the habit of doing it, too. But, it's because my dad told me that if I didn't I would be forcing the starter to turn the A/C compressor when I restarted the engine. This was on a 1972 Pontiac so who knows, it may have been true. I don't think it really matters anymore, but old habits like this are really hard to kick.
I normally turn everything off before shutdown, I want a clean start with minimal electrical load and where I can hear the motor and mechanicals before getting underway (to listen for any unusual sounds/noises). A/C would be no different.
You should shut the A/C down a few Miles/Minutes before you plan to shut off the car but leave the interior fan running.
I figure turning the AC off a few minutes before stopping the car gives the water droplets in the engine bay a chance to evaporate quickly. In any case, I don't want the AC running as soon as I start the car next time. For one, depending on your starting rpm in fast idle (1500-2000 rpm+) your AC compressor spins right up from 0 to higher rpm. The only thing worse is turning it on when at highway speeds (2500+ rpm). Surely this is not ideal for compressor longevity. I'd much rather turn on my AC when the car is at low idle (800-1100 rpm). It will then ramp up with engine speed.
I never gave it much thought. In 40+ years of driving I typically turn AC of heat off just before I shut the engine. I've never had any AC problems, other than Ford's leaking "O" rings, and a pin hole in 20+ year old AC hose.
I will always shut the A/C off before shutting the car down, but usually only a few seconds before.
Don't know why...I leave the heat on when it's cold, never even really thought about shutting that off before shutting the car down unless I expect it to be MUCH warmer the next time I turn the car on.
Don't know why...I leave the heat on when it's cold, never even really thought about shutting that off before shutting the car down unless I expect it to be MUCH warmer the next time I turn the car on.
Originally Posted By: 69GTX
I figure turning the AC off a few minutes before stopping the car gives the water droplets in the engine bay a chance to evaporate quickly. In any case, I don't want the AC running as soon as I start the car next time. For one, depending on your starting rpm in fast idle (1500-2000 rpm+) your AC compressor spins right up from 0 to higher rpm. The only thing worse is turning it on when at highway speeds (2500+ rpm). Surely this is not ideal for compressor longevity. I'd much rather turn on my AC when the car is at low idle (800-1100 rpm). It will then ramp up with engine speed.
the compressor is constantly cycling on and off. even @ highway speeds.
I figure turning the AC off a few minutes before stopping the car gives the water droplets in the engine bay a chance to evaporate quickly. In any case, I don't want the AC running as soon as I start the car next time. For one, depending on your starting rpm in fast idle (1500-2000 rpm+) your AC compressor spins right up from 0 to higher rpm. The only thing worse is turning it on when at highway speeds (2500+ rpm). Surely this is not ideal for compressor longevity. I'd much rather turn on my AC when the car is at low idle (800-1100 rpm). It will then ramp up with engine speed.
the compressor is constantly cycling on and off. even @ highway speeds.
I don't do it before shutdown but I do it before starting. Modern cars should delay the compressor kicking on until oil pressure is up I believe.
Nick1994
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My A/C turns off when I turn the car off. Too hot here to drive without A/C before getting home.
Turn off all electrical load before shutting the engine down.
In my car the AC is always on, even during winter. The climate control uses it for moisture control. Not much point in fiddling with the buttons -- set the temperature and the car decides the level of AC and/or heat. The car has a huge battery in the trunk so that's not an issue.
I always turn off my A/C several minutes before shutting the car off. I hate the smell when the evap is left damp and bacteria grows in there.
Originally Posted By: 55Test
I always do whenever I drive someone's car... Am I just being nitpicky?
Not nitpicky, You are being wise and very respectful toward other people's car.
I always do whenever I drive someone's car... Am I just being nitpicky?
Not nitpicky, You are being wise and very respectful toward other people's car.
I don't think it makes a difference as far as electrical load is concerned. A lot of cars will shot off different systems during cranking, like radio, lights etc.
I do, however, turn off the AC, but leave the fan running, few minutes before arrival to prevent bad smells in manually operated systems.
With auto climate control, I leave the system in auto mode pretty much 100% of the time.
I do, however, turn off the AC, but leave the fan running, few minutes before arrival to prevent bad smells in manually operated systems.
With auto climate control, I leave the system in auto mode pretty much 100% of the time.
Originally Posted By: ARCOgraphite
You should shut the A/C down a few Miles/Minutes before you plan to shut off the car but leave the interior fan running.
+1
https://www.cooltoday.com/blog/musty-smell-coming-from-central-a-c-vents-heres-why
You should shut the A/C down a few Miles/Minutes before you plan to shut off the car but leave the interior fan running.
+1
https://www.cooltoday.com/blog/musty-smell-coming-from-central-a-c-vents-heres-why
Originally Posted By: mightymousetech
I always turn off my A/C several minutes before shutting the car off. I hate the smell when the evap is left damp and bacteria grows in there.
But can you get your wife to do the same?
I always turn off my A/C several minutes before shutting the car off. I hate the smell when the evap is left damp and bacteria grows in there.
But can you get your wife to do the same?
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