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.
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