I need help! I own a 1989 350 5.7 dual fan stock iroc-z, the only upgrade is the flowmaster 80 series muffler that's in it. My problem is that the fan(s) turn on at 240 degrees, prior to this past summer the fan(s) turned on at 220 degrees. I have installed two oem fan switch's, but the problem still perceives. Anyway I sent for the jet chip 200/185 on and off fan switch and th 180 degree stat. The problem is even worse now. The Gauge is now redlining, I have to turn on the a/c to cool it down even when its cool outside, I've done this ever since it started to have this problem. The people at the local Pep Boy's say that it might be electrical. This car is my daily driver, so I need it really bad.

Thanks,
Gerry Soto

P.S. Any help would be greatly appeciated.

 

Get a scantool on it to see if the ECM is commanding the fan to come on and if so what temperature.

If the ECM commands the fan on, but it isn't coming on, you've got a bad relay, bad fan, wiring, etc...

If the ECM isn't commanding the fan to come on, you may have a bad temperature sender (the ECM one).

You can check the fans yourself without a scantool by turning the ignition on and grounding the control ground on each relay.

 

I have this problem too, and I still cant figure it out. I have replaced just about everything(switches and sensors) for the cooling system and my fans still dont kick on untill the temp reaches 250 degrees. Your not the only one with this problem, so if you figure it out, let me know how you fixed it.

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1989 iroc-z 350 TPI, auto trans, leather int. t-tops, edelbrock headers and cat back system, SLP cam, crane double roller chain, 4 wheel disc, and aftermarket hood. Iroc-z's forever, Ford Mustangs NEVER

 

gerry & jermdm,, have you both replaced the temp gauge sensors as well during this troublshooting periood ? if so,, chances are the gauge sensor is at fault for making the problem seem worse.

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