I have read several posts on this forum that look like the same problem, but I have tried what was suggested with no success. My rear heat doesn't work in my 2003 Tahoe. The actuator and heat coil have both been replaced by my mechanic.

It blows air (and properly increases when you turn the speed up), but no hot air. I have tried every setting from AUTO to AUX to just changing the temp and speed with the rear controls in the front of the truck/

Any other suggestions?

I don't want to manually switch it over to heat because it will be getting hot here (Florida) soon. But I do want the heat for my kids in the mornings when it's chilly. Ugh!

 

When you said you replaced the "heat coil" do you mean heater core? Have you tried to turn the tempature control **** to cold does the blower blow cold air? Its possible it could be a blend door problem. The door that controls hot and cold air flow.

 

While we are talking heat. My 97 blows hot up front and cold in the back. When i accelerate i hear a gurgle in the dash around the front heater core. Slow down or stop and it gurgles again upon acceleration. Its not low on water, I've checked it several times. I recently flushed the coolant and put in all new. How did i screw it up? Bob

 

Your problem is you have air in the system. Jack the front end up as high as you can get it. Take the radiator cap off, start the vehicle and turn the temperature control ***** to hot. As the thermostat opens up it will release the air, keep adding coolant until the air is out. Hope this helps.