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Hi everybody
I have on qusetion, Do I need tp turn the ac off when truning off the car engine?
(Sonata 2018)
 

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when i had a remote starter on my old car i would always set it to full blast before turning it off, so when I started the next time, when I got in it was Arctic. With my Sonata I do have a practice of turning it off and running the fan for a minute before i park and shut it off just to dry out the condensation a little. I think it helps, no musty smell after 2 years and no HVAC service done except me changing the cabin filter
 

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why would anyone need to turn off the AC when turning off the car?
Apparently on cars built decades ago, the A/C clutch would remain engaged when the engine turned off. When you went to start the car again, the starter would need to work a little harder to turn both the engine and A/C at the same time, thus wearing out your starter faster. This is no longer an issue with cars. The only reason to turn it off 2-3 minutes before shutting off your car is to reduce the build-up of moisture that eventually overtime leads to the musty smelling A/C.
 

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Well, it certainly did not remain on with the key off. That would have run the battery down. I know that in the 70s (maybe all the way back to when car AC came out), the key switch would drop current to the clutch while the starter was engaged. The clutch would engage as soon as you released the key, but that didn't bother the usually big engines at the time. When engines stared to be computerized in the 80s, the PCMs started keeping the clutch off until the engine reached idle RPM.



Some cars have a blower delay that keeps the blower on for a few minutes after you turn the car off, to dry the evaporator.
 

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2018 Sonata Limited 2.0T (Mfg:11/09/17)
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Well, it certainly did not remain on with the key off. That would have run the battery down...
Back in the early 70's, the A/C clutch would engage for a few seconds after the key was shut off to load down the motor and help prevent the engine from 'run on'. Engines would perculate and knock from leaned-out gas, pre-ignition, and extreme cylinder temps. This was the factory's "Try this, it might work" approach to meeting then new government emissions on some V8 vehicles.

Eventually, carburetors were designed with electrical shut off solenoids in the idle circuit to prevent the 'run on'.
 

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Back in the early 70's, the A/C clutch would engage for a few seconds after the key was shut off to load down the motor and help prevent the engine from 'run on'. ...

I can't dispute that some may have done that. What did the ones without AC do?

My 73 (with AC) handled the problem via an anti-dieseling solenoid. When the key was turned off, the solenoid was de-energized causing the throttle valve to close further.
 

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I’m not aware of damage being caused. It will however dip my RPMs very low briefly after startup. I choose not to do so. My wife has yet to get onboard.
 
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