Defrost and AC question

K_scheeringa · Oct 12, 2007

Is it possible to put a switch inline to disconnect the AC when running the windshield defroster?
I do understand that it does remove the inside fog much quicker with this, but I usually drive with it in the split setting (floor and defrost) and my electric fan (on rad) keeps cycling on and off, plus I’m sure my AC compressor is on at that point.
Looking to not run the AC all winter if possible.

90xj06 · Oct 12, 2007

you could just put a switch in line to the 12 volt clutch wire for the compressor. but i have done this on one of my cars and the defrost does squat. the fan is cycling because freon changes pressure do to temperatures and it will keep cycling because it is "low" but its just because its cold.

bcmaxx · Oct 12, 2007

Why disconnect the a/c from the defrost? It helps dehumidify and accelerates defrosting windows.

K_scheeringa · Oct 12, 2007

But after you get the windows all defrosted your constantly running the ac as you drive along.
I'm looking for a little push button like the imports have.
Is there any wiring in the dash that engages the AC?

darjevon · Oct 12, 2007

just unplug your low pressure sensor (located on the low side line)

Joe

Matthew Currie · Oct 13, 2007

I just unplug mine(the low pressure sensor) in winter.

In answer to the question of why, AC is a nuisance in cool weather and a loss in really cold weather. Although it dehumidifies the air, the cooling effect makes the windshield fog much faster when it's off, which means you must run it constantly. In addition if it's damp outside the outside will fog, and you'll need the wipers. Heated defrost takes a little longer to clear the windshield, but it stays clear and also doesn't fog up on the outside.

K_scheeringa · Oct 13, 2007

Maybe I'll run a wire from the low pressure sensor into the cab and put a switch in there. that way when i need it i can turn it on, but still have the option to turn it off.
I was hoping i could splice into a wire under the dash.

rapom · Oct 21, 2007

You can splice a wire from behind your dash. I did plus I installed a rocker switch to turn the A/C off and on on a blank switch area where the rear window defog switch is.
I used a factory service manual wiring schimatic to locate the wire which is behind the A/C, heating dial. I did this 2 years ago so I forgot what color the wire is. I think it is lime green and it covers all the switch locations except the heater and the vent. (I'm not sure though of the lime green color)

TacticalFats · Oct 21, 2007

rapom said:
You can splice a wire from behind your dash. I did plus I installed a rocker switch to turn the A/C off and on on a blank switch area where the rear window defog switch is.
I used a factory service manual wiring schimatic to locate the wire which is behind the A/C, heating dial. I did this 2 years ago so I forgot what color the wire is. I think it is lime green and it covers all the switch locations except the heater and the vent. (I'm not sure though of the lime green color)

I did the same thing. Pretty easy; it's a very thin, low-voltage wire which I believes is just a ground to the ECU, much like the high-idle wire.

Blaine B. · Oct 21, 2007

I'd like to do the same thing.

You don't have to use the low pressure switch wire though, you can use the wire which engages the A/C clutch, am I right? I'm not sure if the fan will cycle on/off or not still...good question. It won't for sure if you use the low pressure switch wires though.

Defrost and AC question

K_scheeringa

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90xj06

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bcmaxx

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K_scheeringa

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darjevon

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Matthew Currie

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K_scheeringa

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rapom

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TacticalFats

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Blaine B.

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