Question about 2002 Pontiac Grand Prix
I had water leaking down onto the blower and probably also the heater control module which mounts close to the firewall
, behind the blower motor.Now the blower does not run at all, but I did test it by running 12 volts to it directly. The module has 5 wires running into it's plug. I am not able to get any voltage readings at that connector, and it seems I should be getting 12 volts when the fan is set is set to run. I can't find any fuses or circuit breakers. Anyone got any ideas?
There are two fuses for the fan. One is probably a 20 Amp in the fuse panel in the cab and marked "Heater". or "Heater/AC" The second is under the hood may be marked Heater, Blower, or Fan and should be 30 Amp. The one in the cab supplies switched 12 volts to the fan speed switch. The one under the hood supplies the 12 volts to the relay. The relay is normally energized by the 12 volts through the 20 Amp fuse in the cab and through the switch. I think you find that the fan has the normal speeds except for missing HI with the underhood fuse removed, and will turn off with the ignition that way. There is no hazard in operating it that way but you may want to replace the resistor/relay assembly before it gets too cold. The relay is a pretty trouble free device in most cases, maybe you can find a deal on a good one at a junkyard.
The whole idea with the relay under the hood started back in the Sixties believe it or not. There is considerable voltage drop in the wiring between the fan switch and the blower fan motor. By adding the relay under the hood right next to the motor, the voltage drop was reduced, both by the shorter wire, and by using heavier wire to boot. The motor gets really close to the full system voltage when the relay is closed. In your case where the relay keeps the fan running, it can drain a battery rather quickly too!
Posted on Dec 28, 2008
There aren't any fuses there, there is a resistor though near the blower which probably is done and needs to be replaced for about $20 for a new one. See if you can find it, it should look like a multiple of coils.
Posted on Dec 28, 2008
Look at the dic/hvac fuze behind the glove box cover. If it has less the 12 volts on the fuze with the heater blower motor in a middle position and the head light switch off, with engine running it is probably the ignition switch. If the heater blower runs set to max (5), the blower motor is good. If the blower fails to run on some settings other than 5 but runs on others, and you have 12 volts or better on the dic/hvac fuze, it is probably the resistor pack, located behind the blower motor above the floor on the passenger side. If you pull the blower motor, oil the bearings, and check the drain hole is open (engine side). The dic/hvac 20 amp fuze is shared by many circuits, the day time run lights, seat heaters, rear window defogger, and the fancy style heater accessories, depending on the exact year of the car. All these are fed by the 60 amp ignition 2 fuze in the engine fuze block, then through the 20 amp dic/hvac fuze with the key switch in between. The DLR is located above the parking brake peddle but not much appears to go wrong with that but less than 12 volts feeding the DLR will not trigger the day time lights. Mitchell has a complete wiring diagram I got from the web for around 12 bucks, an actually has all the circuits in the set, something like 50 pages of complex diagrams! I found them here: http://www.ahdol.com The diagrams in the usual manuals from Checkers are worthless, as is who ever designed the heater resistor pack placement at GM for the Grand Prix. Hope this helps
Posted on Dec 28, 2008
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Posted on Jan 02, 2017
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