Question about 1999 GMC Sierra

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No heat on our 2006 sierra pick up

Fan is blowing but no heat comea out

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  • Kenny DeLaet Jan 14, 2009

    how do you fix a clogged heater core...can you just switch the lines around and hope it blows out?

  • Kenny DeLaet Jan 14, 2009

    Mine is doing the same I think. Air comes out but its not very hot AT ALL. My temp gauge is reading normal. If it is the heater core clogged, how do you unclog it? reverse the hoses?. Also how do you check the blending door?


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Mine had this pboblem. took it to gm dealership. they wanted $700 for new box. i took it home to chech it out myself and found an ink pen had got through vents and had the heater to defrost door fouled. fixed it in 20 minutes

Posted on Jan 15, 2009

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Does the temperature guage go up to normal if so probably either a bad blend door motor or broken blend door or heater core cloged you can check the lines if one is cooler than the other then it is most likely the cause

Posted on Dec 31, 2008

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