electric radiator fan test - AUSJEEPOFFROAD.COM Jeep News Australia and New Zealand

ingin12 · #1 08-10-2011

I have an electric fan as well as the normal mech fan clutch fan (2 fans) in my 94 XJ. When I have the air con on, the electric fan comes on ok. I understand that if the temp gets excessive, the electric fan will come on (without the air con being on) as assistance to the mech fan.
Last week, my engine got pretty hot (hot day and in city traffic), but I am not sure the electric fan came on. Normally you can hear it, but this time I could not. Is there a test that I can use to see if the sensor is working? or somehow prove the fan is ok before we get really hot weather.

Thanks Ingin

Gtscott · #2 08-10-2011

my brothers 94 xj decided it wouldnt come on even if overheating, unless the aircon was on, so i ended up putting a fan controller on it

ingin12 · #3 08-10-2011

Hi GTscott, Do you have details how you did this? Did you pick the relay by way of a dash switch? I am going to guess that I will have to do something similar.

Regards Ingin

dazza96 · #4 09-10-2011

the sensor that screws in to the thermostate housing is what triggers the fan when overheating cheers daz

rainman · #5 10-10-2011

on the 94 the dash temp gauge sensor and the temp sender for the computer are different.
the service manual has the specs for the computer temp sender (in the thermostat housing)
so you can pull it out and test it.

ingin12 · #6 10-10-2011

Thanks for the info. I have studied the wiring schematics and I cannot find any schematics for the Power Control Module. The ground for the relay pick is from K4 and enters the PCM at plug contact 2. This ground needs to be applied to pin 31 of the PCM to allow the relay to pick and thus applying power to the fan via its contact points. BUT what the hell goes on in the PCM is anyones guess without schematics. How does the ground from pin 2 get to pin 31?
Anyone know where I can get them?

Thanks Ian

rainman · #7 10-10-2011

my understanding was that the pcm controls the grounding of the fan relay. the pcm turns the fan on on when it turns on the air con. and it can turn the fan on when it sensors the engine coolant gets to hot (~105*c.) hence if the sensor is not working properly the PCM may never decide to switch on the fan.