cooling woes

[mkefresh]

I recently purchased a 1985 944- I've started having problems with the temperature. The radiator fans don't run with the heater on, but will work with the A/C. I had the thermocouple replaced, and the mechanic said they installed a new switch. But I'm still running 3/4 up on the temp gauge. Is this a problem with my thermostat?

[carsonmx114]

your fans aren't connected to the heater but they should be on if the engine is as hot as the gauge reads. if you have a three wire thermoswitch you have two speed fans, one wire will be battery voltage into the switch, you should be able to short this wire with each of the other wires to test the relay and the fan motors, one is low speed and the other is high speed. when you turn the a/c on does the temp gauge go down? i had a problem like yours with my 86 and i went all through the cooling system only to find the engine wasn't hot at all but there was a bad ground on the rear of the engine that was making the gauge read high. if the ground is your problem anything you do inside the car that draws amperage will cause the gauge to jump. try hitting your flash to pass or turning your blower fan off and on a couple of times while the engine is running and watch the gauge to see if it jumps.

[mkefresh]

thanks for the info cars! what's going on is the sensor is faulty causing my temp gauge to jump all over the place. that is being replaced this week.

[carsonmx114]

my car did the same thing when i first bought it. before you pay to have a sending unit installed you should hit the dash over the gauge. if this causes the gauge to jump around you have a bad connection behind the gauge. it was in 97 that my car did this but if i remember right there is a resistor on the back of the gauge that broke loose from the circuit board. i hope this info helps you. good luck.