heating up what's the deal

allright I've replaced the mech. fan and t-stat and it's still heating up when I'm running the a/c with out the a/c it's fine what could be the problem. it's a 92' sport 4.0, 5- speed

Is your aux fan coming on when you turn on the A/C?

Dan

yes the aux fan is comeing on when the a/c comes on

does yoru aux fan seem to have as much speed when the a/c is on. if it doesnt, your alternator could be the the problem.

overheater

:banghead: Got some suggestions:
First,been ther done that still doin that!
What thermostat,I've had fewer probs w/180 deg
Last time system back flushed ?
Open/closed system ?
Radiator,GDI (been seeing posts that are saying people are having all sorts of probs w/GDIs some say the are plastic)
Modine name comes up saying they are better,a little more$$ but better.

Here's what I just went through on my 89. Maybe it will help. I have a 3+yr old GDI 3row radiator, newer clutch on my fan, a 99 aux fan, new heater valve (only sat in my rollaway for 2 years...) and ZJ overflow bottle, just converting to an open system about 2 weeks ago. At that time, I also replaced the t-stat.....just because.

After the conversion, it ran too hot, crazy because before the conversion to an open system it rarely got above 210. I also had the water pump start to leak after a 40 minute drive in 95+ heat, running at 220+ degrees.............aarrrrrrrr! New pump goes in the next day.
So I suspect the new t-stat as faulty and buy another Stant Super-stat, this time testing the opening point on the stove using boiling water and a probe thermometer. I discover that neither Stant Super-stat is opening at 195......both barely move at 210, which is as hot as I can get my stove.
I snag another t-stat, this time going with a regular one, not a "Super" model. I notice right off that the standard t-stat spring is something that I can open with my thumbs, I can't budge the spring on the "Super" models.........hmmmm? Maybe Superman could..........?
So I boil test the new t-stat and it opens at 195-200, just like it should.
I installed it and my Jeep is cooling nicely, just like it should. 95+ degrees, AC blasting, stop and go traffic, temp gauge never hits 210.

BTW, I highly recommend the conversion from the closed system to the open system, having already replaced the radiator with a GDI closed type, I did mine by having a local radiator shop build me an inline filler with a pressure cap neck, which I installed in the upper radiator hose. Replacing the old heater valve that always allows hot water to circulate through the heater core made a big difference on the AC performance, once the air inside my black Jeep is cooled down after sitting in the hot sun, I can actually cruise with the AC controls set on Med. and Cool instead of High and Max like I used to, this alone is worth the swap. As for the t-stat problem, this really leaves me torqued. I'm returning both Super models to Moe, Manny and Jack's tomorrow for a full refund. I thought that by purchasing a "premium" unit, I was getting better performance, but this particular experience proved otherwise, hope this is an isolated case, YMMV. Good luck.

thanks for all the suggestions guys I'll be trying some of them this weekend