2003 Tahoe LT w/ Autoride and w/ 3rd row seat. My rear climate control only blows cold air. The front and second row controls for the air are set to a high temp. Everything else on them works great, it just blows cold. What needs fixing? Just wondering if it can be a do it yourself kinda project. Oh and would I find this procedure in a Tahoe manual?

SOURCE: 2001 tahoe front heater not working, rear heater blows warm air

Notorious for plugged heater cores. Also updated plastic restriction couplers mounted at heater core available from dealer. Try back flushing heater core. Run engine till its at operating temperature then carefully hold the inlet and outlet hose breifly with heater fan on high if hoses are nearly the same temp then flow is good , if not then core is plugged.

SOURCE: 2003 chevy tahoe no rear heat

I know the earlier tahoe's have two heater lines running from the engine compartment to the rear under the vechile. Those lines could be clogged or pinched shut. What you do is get two hose locking pliers. Go under your truck, they are two metal lines that turn into rubber and back into metal again farther down the line. First, checked for pinched lines. If none, find where the rubber hoses are, clamp them off, remove from metal lines and drain. Use garden hose to flush fresh water through. When water comes through at high pressure and pretty clear, it should be done. Reconnect hoses, top off radiator fluid and it should be fine.

SOURCE: Air Conditioner blows hot on one side after battery DC

You need to replace the driver side temperature door control actuator. While doing this... make sure you bolt the new one in AND THEN PLUG IT IN or it will spin and not line up in the right place... then there is a series of crazy steps to fix that problem.

SOURCE: 2003 chevy silverado 1500HD LT. A/C fan works intermittently

First check fuses, then test blower motor, Last Temp control switch

SOURCE: 2004 chevy tahoe, dual climate control, blowing different temps

Its more then likely the temp door broken or temp door motor broken/stuck. There is 2-3 of these motors under the dash on the side of the evap/heater core box. Some require extensive labor to replace, good luck