Hey everyone, my 01 Tahoe has no rear heat. I've removed the rear trim panels and checked both blend door actuators and they are working fine. The blower motor works fine. The A/C blows ice cold. The heater lines coming up from under the truck and into the rear are hot. However, when I turn it to the heat setting, no heat! The only thing left that is serviceable or replaceable that I can see is the blower motor resistor. Any thoughts ??
if the blower motor works then it's not the resistor, the motor doesn't know if it is blowing hot or cold it just blows period.
I would "double check" the actuator closest to the blower motor, be sure it turns to heat when you adjust the control and stays there.
if the actuator turns to heat and you still get cold air then remove the actuator and check if the blend door is broken, you will be able to move it by hand when the actuator is removed and you can feel it when it stops either direction.
per your statements the only issue would be.
1. the actuator is not moving to or staying on heat.
2. broken bled door
if both the actuator and blend door check out ok, then the only other issue would be a clogged rear heater core but normally the return line would feel "cooler" than the other line if that was the case