I have a 94z28 the problem is that it does not blow very much heat or hot air. If i change the temp from the red to even the middle it will blow more and if I put it all the way in the blue for air it will blow COLD air great! The hose out of the thermostat housing is hot, and both into the heater core and out are comparable-both hot. I can let it sit for 20 minutes running or driving-it makes no difference. Please help guys. Thanks.

 

I know you say both your heater hoses are hot, but a clogged heater core is the most common cause of no heat. Try flushing the core. What could it hurt?

 

Flushed my core and heat came back... now its been a while and it needs it again...