Pontiac Repair: 2002 Pontiac heater air flow problem, automatic climate control, pontiac grand prix

Question
I have a 2002 Pontiac Grand Prix that occasionally will completely stop blowing air from the heater. The fan always runs to the speed that is selected. I have accessed the air intake side of the fan and can see it running and there is no restrictions. When it stops blowing I can still select defroster only, upper vents or any comination and hear it shifting, but when it quites does not blow air from any outlet. When it stops and when it begins to start working again is over the period of about 2 or so minutes almost making it hard to catch until you notice it is getting cooler when the heat is on. Perhaps you could point me into a direction that would save me a lot of grief trying to locate the problem.

Answer
Hey Denny:

does this car have manual or automatic climate control. Maening does it have dials or a digital diaplay? I assume because you say you can see it runnit it has the digital diaplay and it's automatic????? If that were the case I would lean towards a blower motor control module. that is what controls the speeds of the motor after you selct which spped you want with the control head. The opter possablility is that motor is bad and it quits working and you hit a bump in the road and it turns back on again. The jolt from hitting a bump make it start working again.. Good luck :)


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Now based on the addition information you gave me on the feedback There should be no restriction inside the heater box if one of the mode doors had an issue the air would just be diverted to one of the other passages in the heater EG: defroster,Vent,floor, If the sound of the fan changes but the fan continues to run there could be an issue with the recirculation door but that will not effect the output of the blower motor it just directs where the fan gets it's inlet air from either inside the car or out side of the car. Do any of the heater display segments flash when the heater is on? If so then there is a fault in the system and the flashing segmanets indicate a code is stored in the system. If there were a issue with one of the temp sensors in the heater box it could be effecting the way the blower motor operated whil in the "auto" mode but in manual mode it should not have an effect on the system..