Climate control confusion...

AMGoff · #1 (**permalink**) 11-08-07, 02:23 AM

So I've just started thinking about this now that it's cold out...

When I turn the heat on and don't press the "A/C OFF" button does the condenser continue to run as if the air conditioner were running. If so that would mean that I'm still taking the same fuel economy hit as I do in the summer, correct? Or is the Seville smart enough to know that it's cold and dry outside and should therefor not be running the a/c system?

If it's the latter that would be terrific and I would give kudos to the engineer who designed the system... if not I'd certainly have some choice words for him. I mean, this is a car that's smart enough to tell me that there's Ice Possible (which I thought was really neat, btw), so it should be smart enough to know when and when not to run the a/c.

Either way, until I find out for sure I've been pressing that "A/C OFF" button every time I set my heat to a nice and toasty 80 degrees just to err on the side of caution.

**Playdrv4me** · #2 (**permalink**) 11-08-07, 03:19 AM

If you dont press A/C off it continues to run (though I'm SURE the climate control system and temperature sensors vastly change the way it operates when running it in cold weather, I believe it shuts down below about 35*). It serves for more than just cooling, the A/C also serves to "dry" (dehumidify) the air when the weather outside is cold to assist with moisture buildup and condensation inside the cabin. In addition to that, keeping the A/C entirely off during the winter isnt good for it anyway, as the seals dry out and problems can arise later on.

chubbyranger · #3 (**permalink**) 11-08-07, 06:54 AM

On most cars w/out climate control the AC comes on in the marked AC modes AND the defrost mode for the reason Playdrv says. With the climate controlled cars I believe AC mode is algorithmically driven by a request for cooling and also locks on when you press the Defrost button. The basis of my ignorance here is whether there's a humidity sensor (either engine or cabin) that will cause the HVAC to turn the AC on when its heating the cabin air. Must consult FSM for wisdom...

**Ranger** · #4 (**permalink**) 11-08-07, 12:49 PM

Playdrv nailed it. No humidity sensor. A/C runs in the AUTO mode above 35 degrees ambient or as Chubby said, when in DEFROST mode at any temperature.

AMGoff · #5 (**permalink**) 11-08-07, 01:41 PM

Well I knew that it ran when the defrost is on... I'm not aware of a modern car that doesn't do that.

I just didn't know how "smart" the system was in the Seville. Unless this is something specific to this system, I've never had a problem with any vehicle by not running the A/C through the winter time throughout the years... so I don't quite understand how it could cause any problems by doing so... unless of course this is a specific area of concern with regard to the Seville.

**Playdrv4me** · #6 (**permalink**) 11-08-07, 02:20 PM

Quote:

Originally Posted by AMGoff

Well I knew that it ran when the defrost is on... I'm not aware of a modern car that doesn't do that.

I just didn't know how "smart" the system was in the Seville. Unless this is something specific to this system, I've never had a problem with any vehicle by not running the A/C through the winter time throughout the years... so I don't quite understand how it could cause any problems by doing so... unless of course this is a specific area of concern with regard to the Seville.

Luck. A/C shops in the north get *alot* of spring business from customers who never turn their A/C on in the winter. It's not just refrigerant running through the system, it's OIL for the compressor as well. When you keep an A/C system off for an extended period of time, and especially if you do it repeatedly, the seals in the compressor et al begin to dry up, shrink and become brittle, and then you have leaks (of both the refrigerant AND the all-important oil), and then it's all over.

At the very least, turn it on for 10 or 15 minutes once a month.

**Ranger** · #7 (**permalink**) 11-08-07, 04:17 PM

Once again Platdrv is correct, though I must admit I too am guilty of not doing it as much as I should and have yet to have a problem .....Knock on wood.

No, it is not specific to the Seville. It is generic to all A/C systems.

AMGoff · #8 (**permalink**) 11-08-07, 10:13 PM

Well I fall in the guilty camp with you Ranger... a dozen or so cars over 19 years and I've never ran the A/C once past September... must just be super-lucky I guess.