2003 GMC Envoy, the rear air is not working correctly, have tried replacing the blower motor control/resistor, just tried a different console control, have replaced blower motor, all to no avail. The blower will run when ignition is on, engine is off and blower speed is set to 3 (high), turn engine on or change blower speed and after about 30 sec it shuts off (blower resistor gets super hot and shuts down). Have checked grounds, current draw on blower, everything, can not figure out what is going on.