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Discussion Starter #1
is there any way i can disable the ac from turning on when i use the defroster? it would be more convenient if i could use the ac button to control it. i realize the point of it turning on is to dry the moisture out of the air, however it robs gas mileage to run the ac all the time.

any input would be appreciated.
 

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I think all cars A/C are this way now, not only to dry the air but it keeps the compressor lubed.
 

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BahamaTodd said:
I didnt know they did that on the newer trucks. My AC stays selectable when in defrost mode.
No it doesn't. Trust me even if the light is off the compressor still comes on and there isn't anything you can do about it. Well... i guess you could install a switch in between the clutch wire.

You see the government mandated all new vehicles need to have the AC come on when you use the defroster, this is to ensure quick and good dehumidifying of the moisture on the windsheild.
 

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The mpg increase without the A/C compressor on would be very little anyway. I have driven my truck on the same stretch of highway with and without the A/C running and got the same mpg.
 

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Discussion Starter #7
i just noticed the truck seems sluggish with the defrost on. i havent had my truck long enough to use the ac yet, but i use the defrost almost all the time in the winter.
i figured there might be a simple way of disabling it. maybe a wire u cut connected to the selector switch for the vents?
 

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Discussion Starter #8
there has to be some sort of circuit built into the switch that controls the defroster. because in the normal hi, split, and floor modes the ac is selectable. only when the switch crosses over to defrost/floor and defrost it automatically kicks in.

anyone have a wiring diagram for the climate control? i bet there is a way to disable it, just like daytime running lights or keep the fog lights on when the hi beams are on. anything can be jumped if u know what wires control it.
 

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I don't get it, you WANT the AC to turn on in defrost mode to demumidify the windsheil i don't get why you want to turn it off. The heater alone won't help defrost enough in really humid/cold or warm weather.

Also the AC turning on in defrost mode is built into the BCM's software kinda like how it controls the headlamp or turnsignal DRLs so unless you can reprogram the BCM or get real fancy with some wiring.

Ill try to see if I can come up with anything when i get a chance.
 

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I've done it to mine. I only use the defroster in the winter. Meaning I don't really use any other mode. I do use the ac when I first start it. But once I'm defrosted I turn the ac off for the rest of the trip. Remove your HVAC cluster and take off the cover. If you look at the vent selector you'll notice a tab take trips a switch when you are in defrost mode. I just cliped the tab. Now If I want AC when I'm in defrost mode, I just hit the AC button.
 

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Discussion Starter #11
thank you very much man. i knew they wouldnt do something crazy like program that into the computer.
simple electric circuits man, awesome.
 

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I'll be doing this to mine soon - I prefer the split foot/windshield sometimes.
 

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scott011422 said:
I've done it to mine. I only use the defroster in the winter. Meaning I don't really use any other mode. I do use the ac when I first start it. But once I'm defrosted I turn the ac off for the rest of the trip. Remove your HVAC cluster and take off the cover. If you look at the vent selector you'll notice a tab take trips a switch when you are in defrost mode. I just cliped the tab. Now If I want AC when I'm in defrost mode, I just hit the AC button.
I may sound like an idiot, but can you clarify? By HVAC cluster are you referring to the dashboard switch? Pics of the location of the tab would help, I'd hate to clip a tab and find I did the wrong one.

Thanks
 

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HVAC stands for heating, ventilating, and air conditioning
and the knob the are referring to is the one to the far right that allows you to select the floor vents, dash vents or defrost and so on...

Hope this helps

I think I will be doing this too.
 

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Question about the defrost that I don't believe was mentioned. I have a 05 Colorado with the 2.8 4cyl. The heat works great but when its on the defrost for the windows it does not blow hot or get too warm. Is there anything I can try to fix this? I replaced the blower motor resistor and wire harness cause the heat wouldn't work on any setting except for number 4 full blast.

Sent from AutoGuide.com Free App
 

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It sounds like the blend door is not fully engaging.

You will have to get access to the duct system behind the stereo. Maybe accessible behind the glove box. There is a cam gear that controls the door. It may be misaligned and not allowing the blend door to fully open/close. Look at the gear mechanism and see if it appears to be functioning properly.

It may be a long shot because you do have heat in other selections. But the only reason for air to not be hot is because the door isn't closing off cooler outside air.
 
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