87 4wd cherokee 4.0liter, (kids car).

Thermostat changed, rolled out the fan relay, new fan. old and new fan run fine off a sitting battery yet wont kick on once installed. This is killing me as there really isn't much left to replace.

Any ideas appreciated.

 

Temp sensor?

 

+1. Also, check fuses and there is a relay for the cooling fan in the power center on the right inner fender (I know it's there on the newer models. I'm hoping it's there on yours). It is marked on the inside of the lid which one it is. It could be stuck open and not allowing the fan to kick on when the sending unit tells it to.

Have you turned your a/c on to see if it kicks on when it starts up like it should? If it does, I'd lean towards the sending unit. If not, fuses and/or relay.

 

I changed the relay on the drivers side fender wall to no avail and pulled every fuse I could find and checked those. There are 3 or 4 relays on the other side but I haven't read anything that mentioned them being involved with the cooling/ fan system.

As for the temperature sensor ... where is that, I'd be happy to change it if I knew where it was. As it stands it draws no fluid from the plastic tank and basically runs for about 15min before entering the "danger zone".

Any ideas are appreciated.

 

Oh, sorry - it doesn't work w/ the AC on either. It simply does not work when hooked up at all.

 

one way I checked to see if it worked was by pulling the plug on the sensor on the thermostat housing. once you pull that plug it should automatically turn on and stay on.

 

Not sure where the temp sensor that controls the fan is on the 87, but that is a PRIMARY suspect. Replace it. But be sure you replace the right one.

I know there are two sensors on the older models. (only one for newer) One for the gauge, one for the cooling electronics. I'm sure somebody will chime in and tell you where to look.