I am trying to get the blazer finished up so I can take it to get inspected and all of the sudden the heater quits blowing hot air. It only blows cold air. Every now and again it would cut out for a second but not that often. Not sure if that could be related to the problem but thought I should throw that in there. Does anyone know what the problem could be?

 

Possible reasons are low coolant level, air trapped in the cooling system, clogged heater core, blend door actuator or maybe something else that I can't think of right now...it's hell getting old. And before you ask...no the thermostat isn't the problem.

Under the hood feel both the heater hoses coming out of the firewall. If they're both hot then the problem is most likely the little door that switches between hot and cold air which appears to be a common problem around here but something I haven't had to do yet.

If one hose is hot and the other cold or just barely warm it could be low coolant, air, or clogged core. Less common are problems with the actual heater controls.

 

The good news is you don't need heat to pass inspection

 

That's true but he needs wipers that are not frozen to the undefrosted windshield.