Hi, we are working on a problem with a 2006 Dodge 1500 4x4. Blower fan quit working. Ignition switch was burned, replaced it. Still no fan operation. Then replaced blower motor, heater control unit and resistor. Still no blower. So...here is the funny part. There is 12V at the wire that plugs into the blower when the blower is unplugged and the ground is also good. As soon as we plug in power to fan, total power loss. 0 V! When it's unplugged, the power is back. We then ran a hot wire direct from the battery to the blower and it works, all speeds indicating our new resistor is good. Any ideas?
Cheers,
Len

 

Moved to the correct section.

 

Possibly a Bad head unit. See if the back of it is burnt

 

That was replaced

 

Thank you!