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LhcBrad
11-09-2007, 08:24 PM
My wife runs her heater in her car with the AC button pushed on. She says its no big deal and helps condition the air also makes it less humid in the car. I say you are fighting the comprsesor and hurting your MPG. The heat works when AC is pushed so who is right?

riverroyal
11-09-2007, 09:11 PM
My wife runs her heater in her car with the AC button pushed on. She says its no big deal and helps condition the air also makes it less humid in the car. I say you are fighting the comprsesor and hurting your MPG. The heat works when AC is pushed so who is right?
is a newer car?if so the milage wont change much.My AC has been on in my cars for years,I just adjust the temp.

uvindex
11-09-2007, 09:17 PM
My wife runs her heater in her car with the AC button pushed on. She says its no big deal and helps condition the air also makes it less humid in the car. I say you are fighting the comprsesor and hurting your MPG. The heat works when AC is pushed so who is right?Your wife. :)
The AC does dehumidify the air. The heater and AC aren't really "fighting" since the heater gets its heat "free" (from waste engine heat). The small MPG hit from the AC compressor shouldn't be noticeable.

LhcBrad
11-10-2007, 07:29 AM
I guess i will tell her she was right.

snake321
11-10-2007, 07:38 AM
Whoaaaa, you might wanna rethink going that far....

LhcBrad
11-10-2007, 07:42 AM
nawwww i have a pretty cool wife she wont give me to much of a hard time.
Usualy i am the one whom is right so she has one due to her.

Cheap Thrills
11-10-2007, 07:50 AM
Actually the A/C will De Humidify the air hence the reason the compressor comes on when the controls are set to Defrost/Defog.
T.

CARLSON-JET
11-10-2007, 07:51 AM
she could use the defrost mode or if there is a defrost/foot setting it also does the same thing. On most newer cars the defrost uses the AC to dehumidify. Anytime the defroster is on the AC compressor cycles.

LhcBrad
11-10-2007, 07:54 AM
Yep!! It looks like she is right.

maxwedge
11-10-2007, 07:56 AM
Where is this cold and humid climate you speak of? When it's cold here, the air is already dry as hell. I can't remember ever thinking it would be really great if I could just turn on the AC and make my lips and sinus passages just a bit more crusty.:D

Cigalert
11-10-2007, 07:58 AM
I consider myself a fairly intelligent guy, I've never read the instructions for toilet paper and I can play a mean game of skeeball (that's my criteria for intelligence...I don't care if you agree) but I've always wondered why whenever I use my front window defogger option the A/C kicks on when the window is done getting defrosted. It's automatic. And to think I've been cursing those krauts for screwing it all up. Just like the plane on a treadmill will take off...it all makes sense when it's explained.

LhcBrad
11-10-2007, 08:01 AM
This was discussed when we lived in Illinios. Winters are not fun there it can be cold and humid, and cold and dry, all i know is winters are COLD ,dry or humid.

Boatcop
11-10-2007, 08:04 AM
Your wife. :)
The AC does dehumidify the air. The heater and AC aren't really "fighting" since the heater gets its heat "free" (from waste engine heat). The small MPG hit from the AC compressor shouldn't be noticeable.
I wouldn't call it a "small" hit.
I did an experiment with my Tahoe, just for the hell of it. I set the cruise control at 45 MPH on a level road and waited for the speed to settle out. With the A/C OFF the readout said "4 CYL - 37-39(varied) MPG" (Displacement on demand system) When I hit the A/C button it switched to 8 Cyl - 17-19 MPG.
That's more than a "small" hit.
I suppose it would be less noticeable at higher speeds, but the A/C does cause a big draw on the engine.

IMPATIENT 1
11-10-2007, 12:57 PM
in cool weather , your compressor hardly even strains to work. it'll cycle alot also. when its hot outside, the compressor has the job of pushing hot freon thru the condensor to cool the freon before it gets back to the compressor inlet. during winter months the cabin temp is already low and there's just not much heat to draw outta the air so the compressor doesn't have the strain of high temp , high pressure freon to move;)
can't confirm this with experiments, but i know a/c, and i would think since the pressure and strain on the compressor is considerablly lower, it would take 1/2 the absorbtion power to turn as it does in the summer months. if you understand a/c system and pressures, it makes sense.

LhcBrad
11-10-2007, 01:51 PM
hhhhhmmmm makes a guy think!!!
Thanks for all of your iput on this, the wife did the typical "Told ya so"

SB
11-12-2007, 02:23 PM
No good reason to run the ac in winter.
This is the manufacturer's method of running the ac once in a while during the winter to work the seals, clutch, etc. That way the ac isn't junk when you hit it next summer after 9 months of no use.
The air in winter is dry, no reason to dry it out more.
On older cars, I used to pull the plug on the ac compressor on a long trip, to get better mileage, to keep the ac compressor from running every time I hit defrost.
The mileage hit is significant.