COOLIS

I've started noticing lately that when I have the A/C on in my 1992 SC400 the temperature gauge drops. When the A/C is turned off, the needle on the temperature gauge is about halfway, but when the A/C goes on, it slowly drops down to around the quarter mark. Does anyone know what might be causing this?

sjc2467

It's most likely that the thermostat is sticking open slightly. I'm guessing that it also takes longer to warm up...?

(The cooling fan runs faster with the a/c on, so a leaking thermostat will have much more of an effect with the a/c on.)

COOLIS

I had the car in for service this past week, and the dealer stated everything was operating "as designed" which I am not buying. I'm going to take it in for a second opinion this week.

SCstone

was there any signs of stop-leak in the system? that stuff can gum up your tstat/jiggle valve and heater core. when i first got my sc the needle would dance arround using ac, previous owner used stopleak.. it took a few days getting it all out. the tstat i removed was orange and the jiggle valve was gummed shut and misaligned. make sure the last person who installed tstat alligned jiggle with the protrusion on the water outlet, it looks like a little bump on the outside of the casting.