hi any help my 98 trans am run hot with the ac on. and do not with ac off. can anyone help.thanks

 

Try taking the belt off the A/C pulley and see if it spins freely. May be dragging when engaged.

 

Check your coolant level first. AC puts more load on the cooling system. It sounds like this is enough additional load to cause your car to overheat. This isn't normal so you may need to have your cooling system flushed. Also look at your serpentine belt to see if it is glazed which could let it slip under load. Also look at the radiator to see if it has collected enough bugs, debris ETC. to block airflow through it.

Good luck

 

Have you ever cleaned out the radiator and condenser? The
fins of both, catch a whole lot of fine debris over time. My '02
with only 30K miles coughed up a whole bunch when we had
them loose for cam swap and blew some air through them
backwards. The single biggest problem is airflow obstruction,
followed by fan settings right behind, because the core is too
skinny for the motor (cheapskate GM phuquers).

 

Also check the wind deflector under the car in front of the radiator. If this is missing/messed-up you will get less airflow through the radiator.

 

Make sure your fans are turning on when you operate the A/C. My car actually runs cooler with the a/c on because both fans run automatically. Probably something small like a fuse or fan relay.

 

Clean the rad mine had a walmart bag stup in there at one time

 

Get Bent Thread Jacker!!!!!