Front air cold--rear air hot on 96 chevy gladiator conversion

SOURCE: 2004 chevy subarban blows cold air on one side hot air on other side

i was a GM mechanic for many years, the problem you are having is one of your mode door actuators has gone bad, most of the time it is the actuator on the drivers side that causes the problems, i have seen this many times, sometimes you can take it to the dealer and they can hook the computer up to it and recalibrate it but most times it has to be replaced , it is located under the dash in the area above your gas pedal.

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 air from dash

On most cars when you push a button or slide a lever to change your choice of location where you want the air to blow out louvers move inside the dash to redirect the air to your chosen location. When you switch from heat to AC other louvers move. These louvers are often powered by vacuum lines running from the engine. If one of these louvers is stuck or if you have a vacuum leak in one of the lines it may be causing your problem.

SOURCE: 2002 Tahoe Rear A/C doesn't work

check fuses & power to blower fan motor,plug connections.then apply 12 volts to blower fan motor if it dont turn its bad