no hot air coming out heater vents


Asked by Oct 03, 2007 at 11:58 AM about the 2002 Chevrolet Blazer LS 2-Door 4WD

Question type: Maintenance & Repair

A new radiator, new thermostat, checked all fuses, flushed heater core, checked hoses, still no heat, just blows cold air.  What else can I look for?

Also found a glass fuse on the floor front passenger side.  My outlets don't work now.  Took the cover off and looked, but can't find where the fuse came from.

9 Answers


Honestly, sounds like a broken mix/blend door which is not allowing the hot air in, or else the temp switch is not recognizing the coolant as hot and so not letting it blow into the cabin. There's no reason for a glass fuse to be in this vehicle, as US mfgs. haven't used glass fuses since the 1970s. There must be another reason why your outlets are not working.

10 of 10 people found this helpful.

thank you so much for your reply, how do I fix the mix/blend door of the temp switch?? and if I don't own anything at all that uses glass fuses, and neither do my grandchildren, any guesses at all? I was pretty tired from my job when I got in and went to plug in and charge my tens unit when I saw something fall from that area. It was the next day I saw the glass fuse.

11 of 11 people found this helpful.

My heater quit sending heat and air out the leg area, the rest work fine, how do I fix that?

25 of 25 people found this helpful.

possible blend door issue under dash for your heat...may need the actuator replaced...not positive just a thought

14 of 14 people found this helpful.

possible blown head gaskest,put your hand over ur tailpipe while the vehicle is running if ur hand is wet(not moist) then most likely a blown head

2 of 2 people found this helpful.

I get heat from the top two vents it just quit giving very much heat at the leg selection on the controller.

13 of 13 people found this helpful.

I had no heat coming out of my Blazer. Blower moving air, I could hear flapper valve moving from AC to heater position but no heat. I disconnected the heater core hoses off the top of the engine(squeeze Clamps). Got a small bucket, garden hose with small round nozzle and put one hose in bucket and held hose up to the other and blasted out a lot of brown crud came out. other issues tranny slippage off lights in very hot weather. Replaced radiator. Better. My Blazer had about 110K on it. Auto tranny is cooled by coil in the end cap area of radiator. Also radiator was only 1 inch wide. My Blazer is a 4x4 so they should have put a 2 inch wide one in and also for towing packet. double wide should have been standard in 4x4 and towing. This vehicle was sold in Phx Az summer temps over 110 for month at a time. So it should have never been sold that way. I do not know if it was even an option as I bought as a lease return with 10K miles on it. But I remember early on it had temporary slippage at coming off stop lights in dead of summer until auto tranny fluid cooled down. I would radiator replacement. flush system with pressure hose and replace thermostat. Thermostat should get replaced every 5 years or sooner.

2 of 2 people found this helpful.

Honestly, radiators are so efficient these days... what took inches of core 20 years ago ... now takes an inch or less. Everybody ranks on "cheap" or"thin" cores when it's not the situation at all. Would any manufacturer put out a cooling system that was going to fail in hot weather with the AC on? Not likely. For the record, my '89 K5 had a 3 inch core and my '02 has a 1 inch core and both pull trailers in SoCal heat towing a 32 foot trailer, 14 foot boat on the roof and climbing past Manzanar the way to June Loop at 60 mph climbing over 11,000 feet doing so. Moreso, the "coil" in the radiator is there to make sure the transmission gets to a sufficient temp to stabilize the atf, not necessarily to just cool it. A sin against transmissions is to over cool them. I'm sorry that old wives tales still exist in things mechanical. Your transmission may be dying, but not from a thin or thick radiator core.


Have any of you had a bad battery or replaced a battery and than had this issue with your heater? Think back now, LOL! If so this is a cheap, easy, quick fix that solved the same problem you're all describing. actuator-recalibration-procedure.html and here is a short video to help you along. I did not have the fuse described in the video so I disconnected the battery.

32 of 32 people found this helpful.

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