Where is it located?

OK, so this morning I'm off to go to work, and take the car in. The heat gauge pops back up after about 5 minutes of driving, and the AC starts working. On the hiway won't go over 78C (normally ran at 88C dead set and hardly wondered). Get into traffic and it starts to climb. Hit 90C before I decided to get off the hiway and keep moving. Got to work, and let it sit (all the way up to 93C) to come up. The Fan won't turn on now to cool it down! Clearly the T-stat is buggered hence the low temps....but now the fan going AWOL bothers me.

See the previously posted links on thermostat problems And how to replace it. Fan operation at 93 is normal.

T-stat changed...all is well

Glad you found the problem......

OK...maybe not "all" is well. Keeping a close eye on things, turns out the cooling fan only turns on if the AC is on. Without AC on, the temp keeps climbing. I didn't let it go above 100C. Once I flicked the AC on, the fan came on, and the temp dropped.

Might also explain why the T-stat failed in the first place.

Now, I have to try and figure out why this is happening ...... joys of high mileage cars :(

100C should be no problem (that's 212F, right?) On my SS, the cooling fan doesn't kick on until 216F if I remember right so yours is probably fine. I know that sounds high, but it is a pressurized system. It isn't overheating at that temp and the coolant won't boil till quite a bit higher temps.

Yeah.... I think you are seeing normal operation there......

It always turned on before that, it used to fire up and keep engine temp square at 88C with AC on or not.

Keep in mind I say 100C before I flicked the AC on to turn the fan on. Otherwise I have not gotten the cooling fan to come on without AC on. I can try to let it go a little higher, but as I mentioned, it never did this before. My guess is something is messed with it.

comes on at 103 .... guess I never noticed it before. Learn something new everyday :D

....now, off to change my stablizer links ...... again