Hi everyone, it's been a while since my last post. This forum has been very helpful and I would like to say thank you to all. I have a 02 zr2 blazer, 4.3. Recently did intake manifold gasket. Before the repair my heat would work as long as I kept adding coolant. Now the air coming out of my vents in idle is cold. While driving with heat selector on off position hot air comes out of dash vents. When I turn **** to defrost the air turns cold. I flushed everything including heater core after gasket repair. Both inlet and outlet hose to heater core are hot to the touch. I also burped the air out of cooling system as described in this forum, did it four times, now the radiator and overflow are staying full. Any ideas on what could be wrong? I've put a lot of time and $$$ into her and now it seems the little things are gonna start nickel and diming me. Thanks in advance for the help.