1990 radiator fans

[epaul77055]

One other thing I remember reading, when changing the part have the new one close by in case the Schrader valve leaks a little- (then you can quickly screw the new one on and minimize Freon loss) I didn't have that problem- still working properly to this day.

[Livin' in the 80's]

Originally Posted by epaul77055

yes there is a Schrader valve-very little Freon was lost when putting on the new part. A very short hiss when taking old part off.

My fans are on all of the time. I unplugged the connections and it still runs. does anyone have the fan wiring diagram? Both fans run with Marcs PROM in and all ac switches unpluged and the climate control off. Any input?

[Livin' in the 80's]

Originally Posted by epaul77055

Update: Finally figured it was the A/C requesting the fans. Replaced the A/C Fan pressure switch(the one on the small line closest to the firewall--Took less than 5 minutes) Fans are working properly. Thanks for everybody's input.

How does that sensor work and how did you pin point the switch was bad? If I unplug all sensors, the fan still runs. I get full continuity at the two pins on the switch you are talking about. Is there a way to exactly see what temp the ECM is seeing from the coolant temp sensor?

[Livin' in the 80's]

Originally Posted by Livin' in the 80's

How does that sensor work and how did you pin point the switch was bad? If I unplug all sensors, the fan still runs. I get full continuity at the two pins on the switch you are talking about. Is there a way to exactly see what temp the ECM is seeing from the coolant temp sensor?

Sorted it out. The green connector on the ECM wasn't seated all the way in and I didn't have the PROM snapped in all of the way. All works now.

Lesson learned - pay attention to detail!!!