Honda Repair: 1994 Civic runs very hot when AC is on, head gasket, temperature problem

Question
Hi Bill, I have a 1994 civic LX that keeps overheating when the A/c is on. Started by replacing the thermostat, still overheating in 90 plus weather. I've had radiator pressure tests done by 2 mechanics who say there is no leak. One wants to replace the head gasket for $650, the other said he could find no reason to do that. It seems that coolant is working out of the system over a few days or going into the overflow tank, then the car heats up when AC is on. Runs normal when AC is off. Overflow tank is full when running hot. The fan on the driver's side was off when it first heated up but later appeared to be running. Got any ideas?
Thanks, Steve.  

Answer
Steve:
I would check the water pump to make sure you are getting proper flow and I would bet you're not. You did the easy thing in replacing the thermostat and that is what I always do with a temperature problem since it's cheap. Since the radiator is fine and there is no visible leak the only thing left would be the water pump.
Good luck.
Bill