NUckINg FuTS

I just replaced the fan relay on the driver side fender and the coolant fan switch between #1 and #3 cylinders. Still the fan turns on as soon as I start the engine:mad. It'll turn off a few minutes later but then back on again and stay on:confused: . Any more ideas you guys can throw my way?

-=Jeff=-

which fan is this.. the one in front of the radiator? or the one between the Rad. and motor.

If it is the one between, then that is controlled by the ECM not the Head switch. and the relay for that fan could be bad.. Also that is a sign of a bad MEMCAL or possible bad ECM. are there any codes set?

65Z01

If the main fan it's also possible that the A/C pressure sw (in the A/C line near the blower motor) is acting up. When this sw opens the ECM will turn the main fan On.

NUckINg FuTS

You mean the high side pressure switch, right?

NUckINg FuTS

It's the main fan I'm having trouble with. (between the rad. and motor)

-=Jeff=-

Yep, that head switch is for the AUX fan.. check what 65Z01 and I suggested.. OR

email me and Dirve out to my place on Sat. AM we will find it..

USCZBT

Check your ECT sensor on the front of the manifold under the throttle body. It is next to your cold start injector switch. If the sensor is bad or the connector is unplugged/damaged the Main fan will run constantly to prevent overheating.

fiddleplayer

Mine was on constantly after I blew a radiator hose. I reset the codes and it returned to normal.

NUckINg FuTS

I just replaced the coolant temp sensor with a new one and now i'm getting a code 15. What gives!!! :mad

PeteL

Code 15 is open circuit to the sensor or open sensor.

Pull the plug and short the two wires to the sensor together, you should now get code 14. If you don't get 14 check connector and wires back to ecm. If you get 14 either bad connection to the sensor or bad sensor.

USCZBT

Code 15 is "Coolant Sensor - Signal Voltage High"

NUckINg FuTS

Thanks for the schematic. I installed a new connector and it fixed the code 15 but fan still not turning off. :( :mad


[Modified by NUckINg FuTS, 5:22 PM 5/14/2002]

PeteL

OK, it's the main fan, right?

The things to check here are not alot. The relay is controlled by the ECM. The ECM provides ground to turn the fan on. The AC system also interfaces with the ECM to turn the fan on if AC is requested. So at this point you probably have a bad AC pressure switch, short to ground on the ECM wire to the fan relay, or bad ECM.

I think that's about it. Do you have the shop manual for the car? I hesitate to give information from my 89 as there may be differences.

NUckINg FuTS

Which AC pressure switch can be the culprit? (high or low side) and how would I be able to replace them???

65Z01

My '88 has two connectors close together in the hi-pressure A/C line. The one I mean is the smaller connector with a dk grn and a blk wire comming out.

Since this is a NC switch, pull the connector and jumper the contacts together to see if the fan turns off. If so replace the sensor or just jumper it out if you don't use the A/C often.

NUckINg FuTS

It worked!!! I jumped the switch and my fan turned off, Yippe!!!

Hmmm, maybe this switch was the reason my A/C stopped working a year ago. Interesting. Now I have to figure out how to change it. Can I swap it out?

fiddleplayer

There should be a shraeder valve under the switch. So removing it will not discharge the system.