My car seems to overheat on long drive or AC on when car is idling. My mechanic and I found that it might be the idling problem with the 1992 Lexus ES300. The fan is not spinning fast enough, which caused the temp gauge to move above the halfway mark. We adjusted the idle speed (higher) and it hasn't caused any problem yet. I have been driving for 3 weeks now without any problem. Just try this before someone tells you it's a head gasket, radiator, etc.

 

How do you adjust the idle speed?

 

My guess is they tightened up the throttle cable.

 

Raising the idle speed could just be masking a problem with the power steering system. Another possibility is the IAC valve is dirty and needs attention, hence the low idle. There is no idle speed adjustment on these engines, there is a throttle stop screw that can be moved to bring up the idle, but it is not designed for this purpose.

 

What and where is the IAC valve? Thanks for the info..

 

How to clean IACV

 

Thanks for the info!! Great writeup.

 

Installed new radiator, problem solved. the old radiator was caked with grease and grime.