Thread: AC compressor runs in heat modes on HVAC

Is it normal for the AC compressor to run whenever the HVAC controls are set on anything floor related? (Car is a 04 Impala FWIW)

I'm not crazy about having my AC compressor running all winter long so I thought about bumping up the min IAT to enable AC and see what happens.

normal. pull the ac relay out of the fuse box if you want it to not run.

but then be ready for your defrost functions to not work as well. the air conditioning runs to pull the moisture out of the warm air that is trying to defog your windows. you can guess how much harder it is to defog your windows when the AC is not condensing moisture out of the air

ive ran with the relay out and in, defroster works just fine either way.

but that is why it runs, to help draw moisture out of the air.

Originally Posted by Turbocharged400sbc

but then be ready for your defrost functions to not work as well. the air conditioning runs to pull the moisture out of the warm air that is trying to defog your windows. you can guess how much harder it is to defog your windows when the AC is not condensing moisture out of the air

That's what I figured. I'm fine with it running on defrost, just have never seen a car that runs it on heat (floor). I notice with it blended between floor and vent it doesn't run. I'll try the relay. Worst case I have to put it back in.

Why does it bother you?

Its also made that way to reduce problems with the A/C system that can arise from non-use during an entire winter.

Originally Posted by Turbocharged400sbc

but then be ready for your defrost functions to not work as well. the air conditioning runs to pull the moisture out of the warm air that is trying to defog your windows. you can guess how much harder it is to defog your windows when the AC is not condensing moisture out of the air

People say that all the time yet myself as well as many others have noticed no difference with ac to no ac defrost capabilities. If you ask me, from my experience no ac defrost works better than ac defrost.

Oh, theres a difference.... the conditioned air clears fog much faster before the heater core is hot. But defrost without A/C does work well enough, especially in mild climates.

Defrost and defog. De frost it won't do much. But when it's fogged up like when it rains out - makes a huge difference.

Originally Posted by CrazyGuy03

Why does it bother you?

Because I'm mildly OCD and somehow think it's going to save me a fraction of a mpg, and less wear on the compressor.

So it's something thats been a feature for 11 years on the car and is now a concern??

I mean every single car does this and nobody bats an eye at it.

But it's your car I guess, just seems pointless.

Too bad its not a 99 GP, all you have to do is press the A/C button after startup and it behaves normally but without running the compressor.

In the regal just hit "vent" I think

what about all the cars out there that came with no ac at all? or no working ac in all the cars out there,,,,those guys dont seem to complain about the defroster not working ever, do they?

Originally Posted by ScottyDoggs

what about all the cars out there that came with no ac at all? or no working ac in all the cars out there,,,,those guys dont seem to complain about the defroster not working ever, do they?

That was me, 1980-2009. No choke either half the time. In the south it might be different, so web tales may vary.

GPs don't run the compressor when its below 37 degrees out. Most cars have an easy way to turn it off on the dash. Pulling the relay would remove that daily step though.

I had no A/C for nearly 5 years of owning my grand prix, winter did suck ass when it came to getting my windshield clear right away sometimes. I always had to wait extra long to be able to see.

I'd rather have it working.

Yeah. That's what I said earlier. The heat will DEFROST yer window. The AC helps DEFOG the window

Originally Posted by Fivefingerdeathpunch

I had no A/C for nearly 5 years of owning my grand prix, winter did suck ass when it came to getting my windshield clear right away sometimes. I always had to wait extra long to be able to see.

I'd rather have it working.

We have the opposite problem down here in summer. When it's hot and humid and raining it is nearly impossible to clear a fogged up windshield without having the compressor run. On a side note can't the OP just putt the AC in the off position and use those without the compressor running?

Jeff

nope. the damn thing runs if the heat is on only.