Pontiac Repair: Heater Relay Switch, pontiac montana, metal pipes

Question
QUESTION: 2000 Pontiac Montana - Where is the heater relay sensor in the box? - Which one is it?

ANSWER: Hey Randy:

It is the blower relay your looking for? It's part of the resistor block for the motor. It's mounted in the bottom of the heater box up by the fire wall. It has 3 scres on it with one plug and a 2 wire harness that runs to the motor it's self. Hope that's what you meant. Good luck :}


---------- FOLLOW-UP ----------

QUESTION: No. Here is the problem - no heat. Replaced thermostat; checked heater core; and still no heat. Now checking heater control switch (was told he controls the water intake to the heater core).  If the switch does not open, the water just returns to the radiator and never makes the cycle to the heater core.  Help!

ANSWER: Hey Randy:

No this van the water constantly flows through the heater core Gm hasn't had water shout off's to the front heater core in years for the raer if equipped yes but never the front. with the van hot and running feel the hoses going to the heater core one should be hot and one a bit cooler if they are both cold or one cold and the other hot the core is restricted or plugged. If so take the quick connect hoses off at the metal pipes and run garden hose water in both directions to try to flush out the core. If they are both hot/warm then the water is flowing through the core and the problem is more than likely the temp door in the box not working or is binding up. Hope that sheds a bit more light on it. Good luck :}


---------- FOLLOW-UP ----------

QUESTION: the temp door in the box not working or is binding up - where is this located?  Do not understand temp door? Purchased relays, but not sure which relay controls the heat.

Answer
There is no relay to control the heat...... The temp door is the door inside the HVAC box that directs the air flow between the heater core or the evaorator core. That door is run by a bi directonal motor. here is a quick check turn the fan on hi turn it on to vent position and then turn the temp control to full hot wait about 30 seconds then turn the knob back to full cold you should feel the air flow change a bit and the sound of the fan should also change a bit as the door is moving if you hear or feel the change the door is moving at least some if not then you know the problem is with that. then it can be either the control head or the motor for the temp door.