Rear heat not working ? The blower motor isn't working ? No air coming from the rear vent's ? Is it just a yukon or XL or denali ? What size engine ? 4.8 , 5.3 or 6.0 l Manual or automatic climate control ? Does the blower motor work on any speed ? The front an rear heater system are seperate , have there own electrical circuits . Could have a couple of different systems ,could have a control processor or relay's an a resistor block . Do you know how to test automotive electrical circuit's using a wiring diagram and a DVOM - digital volt ohm meter ? Plus to get at the rear heater-A/C unit you would need to take the right rear trim panel off .
2003 Tahoe No Rear Heat Fix Suburban Yukon XL Repair
The keyless entry system has the following main components:
• The transmitters
• The passenger door module (PDM)
The PDM communicates with the body control module (BCM) through the keyless entry serial data circuit. When you press a button on a transmitter, the transmitter sends a signal to the PDM. The PDM sends a request to the BCM and the BCM performs the appropriate function.
Check the coolant temp. sensor (It controls warm up RPM, open loop ECU mode) And change the fuel filter every 20,000 miles to prevent water in filter from freezing ( fuel starvation).
Actually you can repair them I did mine it was switching to hot on its own I would have to shut the car off and back on to get cold back but I took the actuator off took it apart and the factory greased the thing so much there was a glob of grease that dropped down on the circuit board cleaned it off put it back together and it worked just fine going on the second year still no problem
I worked on a vehicle with same problem turned out to be main fuse in underhood fuse box or it could be fusible link. A spot in the positive battery cable that is an inline fuse. You will notice if it is blown by a break