Trouble Shooting Heater

[Ta-taaa]

I'm new to this site, and if it's as good as the Corvette Forum, I'm sold!

I have a 94 k3500, in great shape. I have not had it very long, but its in great shape.

The Heater and A/C did not work in the truck at first. I replace the Blower motor and got the a/c working.

Now it's cold and I can't seem to get Heat. Raidiator is full of coolant.

I know the heat is controled by a door. I checked the motor on this door and it does not seem to be working when I change the tempeture.

What is this motor called? And how do I do a correct test?

Thanks!!!

[Schrade]

Welcome to the no-games boards!

forums.corvetteforum sucks better than


Is the heater core inlet and outlet hose the same temperature?

[777stickman]

This is out of a '98 C/K manual and your '94 may be entirely different. It may be electric, cable or vacuum.

It's called the "temperature door motor". Look for 3 wires at the motor. Black, Brown & Light Blue. Check for a good ground on the Black. Check for 12v on the Brown with the key in "run". Check for voltage variations on the Lt Blue while turning the temp dial with the key in "run".

Also can you control the air flow from floor to vent and in between?

[Airjer_]

If it has five wires it is the temp door motor. lt. green, lt. blue, drk. blue, black, and tan. Lt. green and blue control the motor. The other three determine the doors posisiton.

[Ta-taaa]

Thanks for the Replys!

Where is the Temp control door located?

[Airjer_]

Probably pretty close to the motor!

[Ta-taaa]

Got it fixed!! It was the heater core. Totaly plugged.Thanks!

[j cAT]

Originally Posted by Ta-taaa

Got it fixed!! It was the heater core. Totaly plugged.Thanks!

since this is a 94 I have seen this problem were it was the OEM SEALANT tablets that caused this blockage....


if not done you should flush out the entire coolant system and if necessary use a coolant flush chemical...

for some reason the heater core is the first indication of coolant issues...as this gets pluged first...