Rear air stopped blowing. Front air works fine. Can i fix this myself. What could be the problem?

please check rear blower heating control actuator.
it appears that this controllers doesnt work from cold to hot

You need to replace the blower motor, and maybe the ballast resistor also.

I have a 2000 GMC Savana Van SLT with front and rear AC/Heat. My front would blow hot while the rear blew cold with AC on. It turned out to be low on Freon. It's hard to know if you have the right amount of freon installed because pressures vary depending on the ambient temperatures. So the best way is to remove all the freon then reinstall the recommended amount as listed on the evaporator housing near the firewall. This worked fine for me... works like new after installing the correct amount of freon.

The dealer messed up. Take it back to dealer for FREE FIX.

TXV - Thermal expansion valve stuck closed . Having a professional A/C repair shop do the testing an fixing .. If you never went to training classes or work on A/C systems , leave it to the professionals .

often on the vans with rear air the air dor acuator goed bad and can no longer switch from hot to cold. also the swich itself will often go bad. this can be caused by sticky fingers damaging the inside of the switch. sometimes a good cleaning in warm water will fix a sticky switch

REMOVE THE BLOWER MOTOR CHECK IT.HOOK IT TO BATTERY TO SEE HOW WELL IT WORKS. IF IT RUN SLOW OR RUN STOP RUN.REPLACE IT.IF IT CHECKS OUT OKAY.THE PROBLEM. COULD BE THE AC+ HEAT- CONTROL MODE SWITCH.

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.

I am having/had the same problem. My rear heater has not worked the last 2 winters, still trying to figure that one out. But I think I solved the front heat problem myself. The heater was blowing cold air while idling and hot air when the car was moving.

I jacked up the front of the vehicle, took the cap off of the reserve tank for the radiator, turned the car on and ran the heat (AC off) for 15 minutes. This is supposed to release any air bubbles in the coolant system and I did see air bubbles emerge as I was watching (this might be normal occurance, I'm far from a mechanical expert). Anyway, this did not immediately solve the problem, still blowing cold air as it sat there idling after 15 minutes. Dejected, I put the cap back on, lowered the vehicle and resigned myself to taking it to a dealer.

But a funny thing happened the next day, the coolant level was a lower (no leaks on the floor) so I filled up, and sure enough, when I started the car and let it warm up a little, hot air started coming out of the heater!!!

As far as my wife knows, I fixed the problem for the price of a bottle of coolant, so I am a hero...but at first I thought it didn't work. Here we are a month later and still blowing warm air and haven't had to replace any more coolant...the internet is a wonderful thing!

Hope this works for you, and I hope I can figure out my rear heater problem as well.

Temp. actuator maybe. A electrica motor that moves a door from cold to hot in the rear HVAC unit . Removing the rear trim panel to get at the auxiliary HVAC unit would need to be done . Search on youtube , video showing how to do it .
Rear auxiliary heat and actuator overview repair for Yukon Tahoe Suburban...
2004 Tahoe rear hvac system only blows cold air diagnosis and temporary fix