Pontiac Repair: No Blower motor for heat and bad rear dfroster, pontiac bonneville, timer module

Question
I have a 1989 Pontiac Bonneville 3.8l with 226,000 Miles
My question is the blower motor will not come I have replaced the motor and resistor to no Avail I do not seem to be getting power to the motor when I tested it is there a way to test the switch and or relay

Second the rear defrost will only stay on for about three minutes any suggestions would be greatly appreciated

Thank you
David

Answer
Hey David.

That is a bit before my time but I'll try to help you out. first off for the motor you have to see if you have power going into the resistor on all the speed settings. check to see that one each speed that one wire at a time has power. If they do then it's more than likely a problem from the resistor to the motor. the relay I think on those older ones is only for HI setting but I could be wrong. look along the fire wall for the relay for the motor. It will have the same color wire that's at the blower motor. a dark purple is the power feed to the motor it's self. it will more than likely have a heavy gauge red or orange wire to that is the power feed into the relay make sure there is power on that as well. check the fuses. Where that relay is there is a bracket with other relays on it if one of the other ones has the same part # stamped on the top of it sawp relays and try that. As for the defroster again I'm not sure if that has seperate timer module for the defogger or it's part of the hvac control head. Either of them could be bad or you could have a bad rear window grid that's drawing too much amperage and it's overloading the timer or the ckt. breaker for the defogger. on both things good luck :)