When my AC is off on my car it will run 180 all day long but when i turn the AC on my temp will start to go up to 260. My fan is on and i have even replaced the motot thinking it was that but it wasent. It overheats on highway driving no stop and go. I wana get this fixed before summer happens. IT was 80 outside the otherday not to hot and it still overheated.

 

It could be a problem with your ac system. Have you added that refrigerant in the can to it?

 

It has been converted to R134 when it was R12 it did the same thing. I checked it last summer and it was a little low so i filled it up and it still wanted to overheat.

 

Thirdgens are notorious for this. Do you have all the plastic installed that sits under and around the front sides of the radiator? If you don't have that stuff installed, there really isn't any good way to get fresh air up and thru the radiator. When was the last time you flushed the coolant system? Could be that the coolant passages in the engine, or the cores in the radiator are plugged up and corroded. Do you know if you have a problem with detonation? That'll drive up the temps real quick. When was the last time you did a full tune-up? DO the compressor bearings make any noise? Maybe those are on there way out and it's putting a higher load on the engine.

 

I would also make sure that your belt isnt too tight or too loose

 

every single one of the 3rd gens i owned ran at 240-260 range and they all had a non working ac...

 

WOW, I have never run that hot. You migbht want to do a tune up. Flsuh your radiator every once in awhile

 

I flushed my radiator a few months ago. I do know the bearings in my tensioner are gone "could that cause the problem" but the tension is fine. I did a tue up about 8 months ago plugs wire cap rotor etc. I have the air dam and all the plastic pices under my car. Today i used it it was about 75 out side and it creeped to about 220 but when it is hotter out 80+ is when it wants to overheat.

 

Any extra resistance is going to increase the workload on the engine, thereby increasing the heat it puts out. You should change the tensioner anyways, if the pulley siezes up, it's gonna throw the belt and leave you stranded

 

I used to go to the car wash and clean out the cooling core in front of the radiator. Use the "tire" cleaning position and you should see the green (just coloring) additive and foaming action. GUNK will also accomplish the same action.

Spray it liberally in the cooling core fins. Wait about 5-10 mins and then hose it out on the "rinse" position. Should reduce some of you operating temp and even lower the cooling temp of your A/C.

I always run my A/C every Wednesday of the week regardless of the weather. Keeps the refrigerant moving and everything else functional so far. I also keep a small thermometer in the lower drivers side vent just to make sure it is the correct temp. Mine blows at 39 degrees on MAX. I just rebuilt it all in Jul of 2002, in Virgina Beach. The humidity was even worse than here in TX.

Jim.