A/C Switch installed. MUST have for us in colder regions

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usar17

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This is amazing, I wish i did it years ago!!!

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/172823116493

Took me about 30min to install this switch, most of which was just removing the bezel. Cut the green wiring leaving the climate control "mode" connector, and added this in using insulated female spades. Lights up when a/c is engaged. My truck was an nice cozy oven today in 'bi-level' mode while its 20° outside. Very helpful for ice on the windshield using 'def'. Or a quick warmup using 'Max'.
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donnieray

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Nice. There are times when the compressor just don't need to run especially in defrost mode.
 

usar17

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Exactly why i did this. So many times i wanted to run heat but not the compressor

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usar17

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In defogging yes. But in defrosting heat is great. Then switch over to cold to finish

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donnieray

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Accually in an A/C system the compressor running aids in defogging it draws humidity out of the air.
My heat only C10 defogs pretty good in the winter, now summer fog could damn sure use an ac compressor.
 

Honky Kong jr

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My heat only C10 defogs pretty good in the winter, now summer fog could damn sure use an ac compressor.
In defogging yes. But in defrosting heat is great. Then switch over to cold to finish

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I wasn’t busting chops just wanted to throw it out there that the A/C is integral in defog defrost too but mostly on defog
 

rpcraft

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Yeah, if you run just the heat when it is cold outside you'll get a lot of moisture and fogging on your windows. It's counter-intuitive but the AC does actually dry out the air more than it cools it. If your HVAC system is working properly the heat should overpower the AC, I think the problem is maybe just no one ever spends much time warming before they drive off and want that instant warmth. Sounds crazy but you might look into placing a heated seat matt on your bench or drivers seat. They make those aftermarket kits you can wire in with a breaker. I was surprised by how much less I use the heater in the car when I got heated seats...
 

usar17

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I really don't have too much issue with the windows fogging up. I primarily use by level mode and it's just nice to have that ambient heat

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twinturbo427

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I was under the assumption that the compressor did not run below 32 degrees F and/or when the engine temp was below some pre-set threshold(cold weather only <32) or some combination.

Now what year/model that was for has been lost to time and overwatching Ren & Stimpy while listening to Slayer. :doh2:
My knowledge of cold weather mechanicking is limited. LoL

I do recall my father unplugging the a/c compressor during the winter on the pre-72 Chevys we had when I was a kid. Better gas mileage?
 

usar17

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Id assume no compressor running helps a little. Theres nothing fancy enough on my 85 to disable the compressor under a certain temp lol

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rt66paul

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There are hair drier units(mostly for VWs) that will warm up the cab and help defrost/defog the windows(they plug in to the ciggie lighter). Maybe that is to lo-tech, but it does work...
 

Rusty Nail

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Sure unplugging the compressor was common knowledge back in the day but let me tell you somethin.
I unplugged the compressor in the last gmt400 i'll ever own and it lunched. Some ******** about it HAS to circulate oil or yep, sure nuff locked it up.

I'll never own another one of those pieces of ****, tell ya what. Matter of fact, I didn't buy that one, for the record - it was a gift.
 

CorvairGeek

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The A/C cycling switch opens at a pressure which equates to just above freezing. The same is true for the older systems (like my '78) that have a mechanical thermostat at the evaporator (and low pressure switch). Once the vehicle is warmed up enough, i.e. significant warmth under the hood, the system will start to operate again.
The constant run systems, '73-'74, IIRC, are probably like the cars with the thermal fuse / limiter.
 

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Id assume no compressor running helps a little. Theres nothing fancy enough on my 85 to disable the compressor under a certain temp lol

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I think it would definitely help at first start and while de-icing while maybe you are indoors withe the truck warming up while idling and things like that, but once someone gets in the vehicle and starts mouth breathing it'll probably be a short time before it needs to be cycled on for removing the moisture and defogging.
 

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