HVAC question- Is it "bad" to shut off AC compressor while it's on?

[Rochev]

I never shut off my house or car ac if the compressor is running. On my new window AC's, when you turn it off it will shut off the compressor but actually wait several seconds to turn the fan off if the compressor is running. On my cars, I'll shut the ac off but leave the air on before shutting that off, then the engine. Is this an ocd issue or am I doing the compressor a favor?

 

[Blinker]

This is ocd.

 

[TmanP]

It shouldn't make any difference to the compressor either way; the only thing you might be doing here is drying the evaporator coil with the extra bit of airflow (not letting it sit as cold and damp right after the compressor shuts off). Compressors (at least in window a/c units and car a/c systems) are either on or off, so if you ever shut if off, you will shut if off when it is "on" (as per the title question).

If it's warm when I park my car and it seems like I'll need it next time I drive, I leave the a/c on. I wouldn't overthink it unless you are having odor issues.

 

[nomas]

Who put that silly crap in your head ? He should be whipped ...

 

[Rochev]

I read that somewhere a long time ago and never thought much of it until recently. It said something like it being as bad as turning it off and on (where the compressor won't come on for a bit) I guess my ocd comes in handy a little, because when I put it on fan mode before shutting it off, it at least still blows out cold air for a whole 10 seconds

 

[Nick1994]

The compressor is either on or off either way. Doesn't make a difference.

More wear and tear on your switches and buttons than anything.

 

[PandaBear]

The only thing bad would be right after you turn it off, turn it back on (but the thermostat should have a timer to prevent that anyways).

 

[bullwinkle]

Compressors turn themselves on & off all the time-when the low side gets cold/low pressure enough (automotive, to prevent coil freezing up), or regular building A/C makes thermostat setpoint. This happens all the time, by itself, it's not going to shorten the life of anything.

 

[Lubener]

Shutting off the compressor manually is no different than the thermostat doing its job.

 

[tcp71]

I actually shut off the AC a few blocks from home. Not for the compressor, but to dry the air passage and evaporator to try to reduce any humidity that will cause odors. Not sure if it works...

 

[kschachn]

I never shut off my house or car ac if the compressor is running. On my new window AC's, when you turn it off it will shut off the compressor but actually wait several seconds to turn the fan off if the compressor is running. On my cars, I'll shut the ac off but leave the air on before shutting that off, then the engine. Is this an ocd issue or am I doing the compressor a favor?

How do you shut off the compressor if it is not running?

 

[Snowflake White]

I think the main thing is you do NOT want to shut off the compressor and then immediately turn it back on within seconds, this could strain it.
But as far as turning it on and off normally there is absolutely no problem.

OP relax and enjoy the AC.

 

[Dave Sherman]

The compressor normally cycles off from the thermostat, not sure how turning it off is any different; in either case the contactor turns off the compressor exactly the same way. Only reason some thermostats keep the fan running is so you get some more cool out of the coil, and maybe to help prevent mold, but it makes no difference to the compressor.

Turning the compressor back on immediately after turning it off IS a big deal however, since trying to start while the high side pressure is still up may stall it, making a breaker trip or having the thermal overload trip. A lot of newer digital thermostats have a delay built in to prevent that though.

 

[gathermewool]

I actually shut off the AC a few blocks from home. Not for the compressor, but to dry the air passage and evaporator to try to reduce any humidity that will cause odors. Not sure if it works...

It does work. I switched to this method for all AC units I own (except my wife’s Forester - she does her own thing). None of the evaps emit that mildew smell except for the Forster, just a little.

I‘ve actually explained the situation to her more recently, so she at least switches the window units to fan for a while before shutting them off for extended periods. No more smells, like I used to experience before implementing this practice.

 

[Rochev]

Maybe I misread that article all those years ago, they could have said what was mentioned- shutting off the ac and leaving the air blowing for a minute can help reduce moisture and mildew buildup. That's what I've always done anyways

 

[Chris142]

The compressor cycles on and off when driving anyway.