Mechanics

GMC JIMMY HEATER PROBLEM

1999 GMC Jimmy • 185,000 miles

My heater is blowing out cold air, I am trying to figure out if its the heating controls or the hot cold flapper (cold hot dock, or vacuum actuator). How do figure out what the problem is between those two. I have already canceled out, coolant, thermostat, water pump, and the heatig core.
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Kikielizabeth7
January 31, 2013.



Do you live in an extremely cold region? Does the engine reach normal operating temp? What is your normal operating temp in degrees F? Do the heater hoses get hot? You might check for applicable hvac trouble codes. Some of the national brand autostores check codes for free.
If a temp door under the dash is having a problem, I'd have to get under the dash and check it out.


JDL
Jan 31, 2013.