hello...I have an 85 GS with air added on in 2007. With the AC off, the car seems to run a little hot but not enough to concern me. When i turn the AC on, it heats up more. If I maintain +/-50 or more MPH, the temp gauge stays below 1/2. When I come off the highway with the AC on, it heats to 1/2 and frequently above that. I've changed the coolant. No improvement.
Has anybody else experienced this? If so, what was the fix? I'm thinking the radiator may be clogged, maybe a bad thermostat or water pump.
Any input would be greatly appreciated.

Thanks,
Mike

 

Does it get hot when idling? Radiator fan could be the culprit if it does.

 

have you checked the radiator cap? sometimes a worn-out cap can cause pressure loss and overheating. might be worth a shot?

 

It will get hot at idle with the AC on. If the AC is off, it isn't a problem. The fan appears to work properly but I understand what you are saying. I had not mentioned that the solenoid that kicks in a higher idle speed with the AC on isn't working. I created a spacer on the solenoid cable to keep it at higher idle with the AC on or off. It sees to have helped a bit, but not entirely. I'm considering some of the possible causes that seem most likely to me. So far I have
1) possible blockage somewhere in the coolant system
2) bad thermostat
3) the aftermarket AC design being poor & just overwhelming the stock cooling system
4) the fact that the oil cooler blocks so much of the radiator
Not sure where I'm going to go from here.

 

I haven't properly checked the radiator cap yet. It appears to be holding pressure ok. I may test it as part of trying to figure this out