David Hawk

I have an 2001 and the other night while driving with the defrost on I hit the mirror defrost button and all the hvac shut off. I've replace the fuse, relay, resistor and checked the blower motor which is working when power is put to it. I've bought 4 climate control panels and still nothing I can hear the vacuum in the system when I change between doors but the blower will not come on.

Busboy

The blower motor has a fuse in the PDC and the relay has a fuse #2 in the junction box fuse panel inside the cab. When the relay is energized power is sent directly to the blower motor and it's the ground that is varied for the different speeds through the resistor block. In High fan mode the resistor block is bypassed so if the motor will not run on high I would check the ground wire at it's termination, G201 is on the right center dash support. First check the 2 fuses then listen for the relay operating, if the relay does not operate then no power will go to the blower motor, the relay is operated by turning on the ign switch, turning on the blower is done by providing a ground. If the relay is working and the fuses are good then I would check the electrical pins on the connector of the fan control panel, if as you say you have replaced it 4 times then look at the connector pins.