I changed the thermostat, and the heater core is not leaking just not getting hot.. really starting to get to me. some1 looked at it and told me it was the "glen door" or something like that.. please some one e-mail me some options, or soultions. thanks

chris

 

they were probably referring to your "blend door". Do a quick search on the forum for more info.

 

have you tried to bleed the coolant system i have had the problem before and that did the trick

 

had the same issue on my '02 4x4 blazer, I took the hoses loose (heater core) that goes into the water pump and motor and basically flushed water through the heater core and its been blowing hot every since.

 

CLR flushed through the heater core then rinse will do the trick!

 

You need to decide what is wrong before you waste any time trying to fix something that does not need fixing.
With the engine at normal operating temp. both heater hoses should be hot to the touch. If so you may have a blend door problem.
If one is warm or hot and the other one is much cooler the heater core is restricted.