Just a quick thanks for the helpful people here on the forums.
I had a "cool" heater problem on my '05, 80,000 blzr.
Changing the stat produced no joy.
After doing lots of reading I found where someone mentioned in-coming heater hose hot
out-going hose cool= reduced flow in heater core, was spot on!

I removed the hoses @ pump/manifold and applied a garden hose enema, reattached hoses/refilled.
Now the heat coming out of the dash outlets will fry an egg just like it was when new.
It will get a complete/total system flush in the spring, replacing the Death-A-Cool with the good green stuff.
Thanks again,
ol'George

 

Glad it all worked out, great group here, some smart people, (I`m not one) but learning

 

You are welcome, and we are all proud to read user responses. This is a hell of a group of guys and gals. Stick around.