specialkeay

I have a 1999 grand cherokee 4.0 .I have had the fan clutch relay replaced 3 times. Every time I bring it to the shop thats what they fix, they havent looked in to why it keeps going. If I leave it plugged in it just stays on even when the car is off. so I have to leave it unplugged or the battery will die . Which is fine now because its winter now, unless I leave it idleing then it will over heat. I had to have the head gasket replaced because I over heated when I was stuck in traffic a few months ago. So this has allready cost me a pritty penny and its still not fixed. Any help would be much appreaciated.

Bustedback

Are you taking it to a Jeep dealer, or an independant repair shop?

specialkeay

A private shop

OrvisKrawler

sounds like you need to find a new shop that knows how to diagnose problems

5-90

1) If you note your temperature climbing, roll down the windows and turn the heater on full! That will help cool your engine...

2) There's no "fan clutch relay" - the thermal fan clutch is a mechanical device (temperature-variable viscous fluid coupling,) while the fan relay is for the auxiliary electric fan (you probably have two fans.)

The "fan relay" is tripped in one of two cases:
- The ECU sends out an "AC REQ" (Air Conditioning REQuest) signal to the relay, to accommodate the additional thermal load of the aircon system.
- The ECU senses the coolant temperature being above a threshhold value (~220-225*F for the 6-242) and tries to cool the engine down.

What are your symptoms? If it's just the fan staying on with the vehicle off, you have a wiring fault that keeps the relay coil energised. The relay doesn't want replacing, the wiring wants checking - and you're going to want a decent set of wiring diagrams to do the job (so you know what you're looking at.) If you're a neophyte at electric work, I'd suggest help as well - wiring faults tend to be fairly obvious on a visual inspection (burned bits, exposed copper, ...) but you'll want to make sure you're looking at the correct wiring - which is where you'll want to make sure you - or someone there - knows how to read wiring diagrams properly. It's not difficult, it just takes a bit of practise...