My 95 EF wagon cooling fans drop out of their high speed range at some stage during driving (even when i keep AC on and cabin fan in HI). They drop out once a bit of heat builds up under the bonnet.

My question: What might be the likely cause for the fans to drop out when the AC on/cabin fan in HI condition is present?

I was thinking crook relay? Any ideas?

Replaced:

Waterpump
Thermoswitch (Genuine)
Coolant
Thermostat (Genuine)

Radiator flushed

I had a thermo fan relay go on my EL fairmont at about 150000km, only one fan was coming on, temp was climbing at traffic stops. Just followed the gregorys manual process of fault finding with a multimeter and found I had a dud thermofan relay. Got a Narva 40A relay for $10 and it solved the problem......

BTW should have checked the thermo fan relays first up. common problem with EF,EL's due to the high current drawn through them...

Also to test your coolant temp sensor on the thermostat housing, just unplug it while the motor is running the fans should come on full speed. If they don't it''s the sensor or relay not latching....Use a mulitimeter and gregory's manual resistance values to check the sensor is within range.

If you don't have access to a multimeter put the dash in diagnostic mode as per website and you can see the coolant temp sensor values.

Also check out the doco's on here and pull the fault codes from the ECU, all the relays have a code.

If I start vehicle with AC on and cabin fan in HI position, the fans are on immediately and stay on until I notice the temp gauge comes up. I then have to pull over, visual inspection will confirm fans not at high speed, have to stop the engine, restart and they come on again.

Its not the thermoswitch as I have replaced that and the fans go to high speed if that is disconnected whilst its running.

I just want to make sure the fans stay on when they are suppossed to (i.e. AC on and cabin fan on HI). I can live with that for a while. It runs very cool providing the fans stay on with A/C, usually around the 75-80c mark. Without them it gets up near 100c.

I'll throw some relays at it and see how it goes....

finally figured this out....after much trial and error, I discovered the Cam Angle Sensor was not aligned correctly.....I had swapped the motors and just installed the Cam Angle Sensor the way it came out of the original motor..obviously it was not installed right in the original motor to begin with

now correctly aligned, my cooling issues have gone (temp gauge never gets over A in Normal now), the engine torque between 2000-3000rpm has come back, erratic idle issues have dissapeared, fans operating correctly...

the ECU must have been having a hard time trying to stabilise things...

how do you check that the cam angle sensor is aligned properly?