Question about 2004 Chevrolet TrailBlazer
Thanks for using FixYa. Try and check if the heater core is plugged. Find the 2 coolant lines going to the heater core. They are right next to each other with approx 3/4" hoses going to the engine. Now, warm up the engine with the heater on max (don’t turn on the fan). Next, feel if the hoses are warm (maybe HOT!) If they are not warm, then you most likely have a plugged core. A back flush will resolve the issue. If your hoses are warm, turn on the fan. One hose should go cold (or cooler than the other, actually should be about the same temp as the air from your air vents, if there is a plug). If both hoses are hot and stay hot, and you have no heat, then the problem is not with the heater core but with the blend doors.
There are electric motors that operate the "blend doors" inside the dash directing air flow from the heater core and A/C evaporator core to the cab of the vehicle. If you feel a drastic difference in one of the radiator hoses, then try replacing the thermostat and see what happens. If all the heater and radiator hoses are pretty much the same temperature I would suspect a control problem in the dash controls or in the blend door operation. You’ll need to remove the dash to check these.
Please do accept the solution if the issue is resolved or else revert for further assistance.
Posted on Feb 08, 2010
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Posted on Jan 02, 2017
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