COOLING FANS ???
03-26-2015, 05:29 PM
#1
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Car: 91 R/S , 89 dodge p/u
Engine: L31 GM crate re-cammed , 318
Transmission: T-5 , 4 speed auto
Axle/Gears: 3.42 , ?
COOLING FANS ???
while doing a little cleaning and checking last week , I noticed my cooling fan came on when defrost selected . I know they should/do come on when A/C is selected . maybe I just never noticed before . does anyone know if they should come on when defrost selected ??? thanks in advance ...
03-26-2015, 06:01 PM
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Car: 89 forrmula
Engine: 350 TBI
Transmission: T-5
Axle/Gears: 3.55
Re: COOLING FANS ???
If the compressor gets cycled (which it does when you select defrost mode) it triggers the fan relay. Newer vehicles usually use a trinary switch circuit in place of this method.
03-27-2015, 05:51 PM
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Car: 91 R/S , 89 dodge p/u
Engine: L31 GM crate re-cammed , 318
Transmission: T-5 , 4 speed auto
Axle/Gears: 3.42 , ?
Re: COOLING FANS ???
thanks , never too old to learn (damn I'm old) . 
03-31-2015, 08:57 PM
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Re: COOLING FANS ???
In defrost mode the AC compressor runs to provide de-humidified air if the outside temperature is above 40F. When the compressor is running the engine cooling fan(s) will run as well.
De-humidified air helps clear the inside of the windshield.
De-humidified air helps clear the inside of the windshield.
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