2001 chevy suburban heater is not working front and back it blows air but not hot air

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: Chevy Suburban Front A/C not blowing/not cold

i had the same problem, i changed out the complete front control panel and now it works like a charm.

SOURCE: Rear a/c not blowing cold, front works fine.

you may not have enough refrigerant. a low charge can cause the rear in this dual system to not work for beans. charge with a can of uv and find the leak. fix the leak. evac the system and recharge. i think you take 4 lbs, but check the accumulator sticker. you may want to just change the accum at the same time.

SOURCE: 2004 chevrolet suburban AC blows hot/cold at same time

You need to replace the drivers side temp actuator that is located on the left side of the HVAC box. It is retained by 3 screws and is fairly easy to replace.

SOURCE: 96 suburban air conditioning blows out cool in front hot air back

Am investigating same problem. Download the free technical manual and you can find a diagram for the air mix door. If this doesn't shut you will be getting lots of heat through despite the cooling of the Aircon. I don't know how to get at it or fix it but it describes how to run diagnostics - you don't need specialist tools for this. Also a blocked pollen filter probably won't help.