rear AC blower

[kebauc]

I posted this originally in the Chev forum, but am about to give up and take this thing to the dealer. I just wanted to give the GMC side of the house a shot at it.

The rear AC blower does not work. I took off the interior panel to get at everything. When changing the fan speed switch, there was an audible click from the relays in the resistor changing position. There was no voltage on the connector to the blower motor.

So, I replaced the resistor module. Still have the clicks (good), I have 12V on the output (also good), but no motion from the motor.

So I got a new motor, and that does not work either.

The particulars on the truck are

2003 1/2 Ton Suburban.
The engine is the basic V-8 GM sticks in these. I gave up keeping the size designation straight when everything went to liters. I guess it translates to 350 or so. This is also a 100% manual HVAC. No automatic climate control here.

Any help is appreciated.

[2000CAYukon]

You have 12 volts at the blower motor connector? If so, it should turn. Perhaps the new one is also bad.

Using fused jumpers from the battery, test the blower motor and see if it works.

//2000CAYukon

[kebauc]

The motor seems to be OK. I put a power supply on it and got it to move.

I am thinking now that there is a weak connection somewhere. When in measure voltage without a load on it it comes up OK. I am betting that once the motor load is applied, the voltage drops off and the motor will not turn.

Time to get out the multimeter again and crawl down the wiring.

[2000CAYukon]

Make sure the ground is good and clean. Not sure where the ground is for the rear blower but it could be the source of your problem.

//2000CAYukon

[kebauc]

The ground is good. I measure about .1 ohm from the motor pigtail to the body of the truck.

I checked the current draw with a small bulb, and basically got nothing. Somewhere in the maze a wire is likely a bad hot wire.

Anyone got a wiring diagram? You can email me at my forum name (at) gmail.com

Thanks!