Question about 1999 Chevrolet Blazer

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Heater problem My 1999 blazer does not give much heat. If I put the selector switch to the A/C mode and put the temp dial to hot I then get alot more heat. But when I use the heat settings the correct way I don't get much heat and it does not seem to blow out as much air as it used to. The heater core is not plugged at all. I am thinking this has something to do with the flaps or something not working correctly under the dash. Any help with this would be greatly appeciated.

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  • upmaine Sep 22, 2008

    Yes I have the correct T-stat in it. The coolant temp gets plenty hot. The blower motor works great. When you use the A/C the blower kicks out all kinds of air but when you switch it over to heat it's almost like something does not open up all the way and you can almost hear the blower working harder lke something is shut and it's trying to force the air thru.

  • upmaine Sep 25, 2008

    There is no button of any kind that that allows you to control the fresh air intake in this blazer.

  • upmaine Oct 07, 2008

    Flushing the Heater core was the first thing I did and there was no blockage at all. The water flowed thru the Heater core just fine.

  • victor diaZ Jan 09, 2009

    my heater on ;my blazer really doesnt blow out air you just hear the blower kicking in der only lil air on da dash

  • Anonymous Mar 26, 2014

    will not put out hot air when temp dial set to hot



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Try to flush the heater core in reverse cause I had this problem once and my buddy who is a mechanic told me to flush the heater in reverse thoughcause then it will unplug it self does sound like it makes much sence but worked on my blazer just try it and see if it get better for u

Posted on Oct 07, 2008

  • 05vrod Oct 07, 2008

    try to flush the heater core in reverse cause I had this problem once and my buddy who is a mechanic told me to flush the heater in reverse though cause then it will unplug it self doesn't sound like it makes any sence but it worked on my 2000 ZR2 Blazer just try it and see if it gets better for u


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This is a silly suggestion, but under the temp/blower gauges there is a button that gives you the option to bring air in from outside or circulate it from within the vehicle. Try toggeling it?

Posted on Sep 25, 2008

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Do you have the correct thermostat in the vehicle? it is possible that the blower motor and or it's controls are going bad. if you have a cooler themostat in the car the heat will be less hot because it circulates more frequently and does not get as hot as it would with a hotter / correct thermostat.

Posted on Sep 22, 2008

  • bryant smith
    bryant smith Sep 22, 2008

    i'm not 100% sure but, i'm pretty sure that the controls are vaccuum. a vaccuum line could have broken (usually don't fall off). it could be in the dash (at the controls, less than likely), it could be under the glove box (usually the problem). sometimes (more often than not) you have to remove the glovebox in order to get a GOOD look at what's going on. most of the time the major control lines (vaccuum or electrical) are in that area.


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1 Answer

Why does my heater only blow hot air?

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