Tom

Tom,

Q I own a ‘98 Chevy Blazer. When I turn on the heat only cool air blows.

What should I do? It’s cold here in Brooklyn during the winter!

Lisa—Brooklyn,  New York

Lisa,

A I know all too well the cold of New York City, having grown up in

Brooklyn myself. The basics of heater diagnosis begin with checking the
coolant level. Make sure it’s full. If the coolant is full, then check the
thermostat and make sure it’s opening at the proper temperature (usually
about 212 degrees Fahrenheit) and that there is proper coolant flow. If the
thermostat is good, check to see if the heater core is plugged. You can do this
by checking the heater hose temperature. If one is hot and the other cold, the
core is plugged and you need to replace it. If not, then the problem probably
lies in the HVAC duct system, and the dash needs to be disassembled to find
the problem. It’s orobably a stuck air-blend door.