Jeep cooling system problems

[steve]

My oldest son has a 99 grand cherokee. Last night the a/c started to blow warm air at a stop light and then the temp gauge jumped up to the red in a matter of seconds. He let the engine cool down and checked the colant level. It was full . He drove it home without the a/c and evertything was ok.However if you turn on the air it blows hot and up goes the temp gauge. Any ideas. Thansk.

[minniemobuddha]

it sound like a cooling fan issue,possibly with a relay or switch,or a fan motor problem.if its just when the ac is turned on it could be a relay.do you hear a belt squeal?if so the ac compressor is locked up,not allowing the belt to turn the water pump.kinda remote but the chacne is there.hope this helps

[steve]

Thanks for the reply . You were correct on your diagnosis. The fan relay was bad as well as a relay on the air conditioning.A two for one deal. Then a couple of days later the battery shot craps. The bad battery became evildent when the truck was running rought at idle. Thanks.

[shinnery]

I have a 92 Dodge D250 CTD (228k mi.) that last summer got to overheating when you used the A/C. Got to looking at it and when the A/C compressor clutch kicked in the serpentine belt STOPPED. No smoke or anything. I went and bought a new belt and tensioner. Put them both on and no more problems. I would have never thought that crank pully would spin in that serpentine belt without burning it in two.
Bryce