1995 Chevy Impala cooling fans

MUNDO1954

MEMBER
1995 CHEVROLET IMPALA
V8
2WD
AUTOMATIC
190,000 MILES

The cooling fans wont come on at all and the car overheats. The fuses and relays are good and I have replaced the temperature sensor and they still don't come on. If I disconnect the wires going to the temp sensor, both cooling fans come on and stay on until I connect the wires back and then they shut off again. The voltage to the temp sensor is 5 volts which is what its suppose to be. There is also no engine lite on.

3 Replies

DOCFIXIT

MECHANIC
18,828 POSTS

Do fans come on with the AC? Check for ground on purple wire you have 5v on yellow. The temp sensor you replaced near thermostat housing?

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Monday, May 18th, 2020 AT 5:43 PM

MUNDO1954

MEMBER
2 POSTS

The a/c is low on refrigerant so the a/c wont activate the the clutch assembly. I checked the purple to ground and there's about 8 ohms of resistance. I turned on the a/c anyway but the fans didn't come on.

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Monday, May 18th, 2020 AT 5:43 PM

DOCFIXIT

MECHANIC
18,828 POSTS

There should be 0 ohms on ppl wire. The 5v go through thermister as temp goes up so does resistence and less voltage gets back to PCM. Which in turn grounds relays for fans. So when you disconnect your signaling PCM engine is max hot 0 volts returned. Ohm across two terms on temp sensor start cold then check as it warms up. If resistence goes up then sensor O.K. Then PCM becomes suspect.

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Monday, May 18th, 2020 AT 5:43 PM