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Chevrolet Blazer Heating and Air Conditioning



  • dfhltddfhltd Posts: 11
    To tell if the thermostat is bad, look at the temp gage on the dash. It shoulkd be in the middle. If it's way in the cold zone it's no good. Assuming the coolant in the engine is hot according to the gage then the heater should be getting hot coolant. Find the two hoses that connect the heater to the engine and wrap your hand around them to see if hot coolant is flowing in them or not. If they are hot you have a problem with the air doors inside the heater and the control that adjusts how much hot and cold air to mix. Yours could be stuck sending all outside cold air and no warm air. I don't know about your model but some have a water control valve that controls the volume of hot water the heater gets. It might be stuck shut. find it and test it to see if it opens and closes when you apply 12v to the terminals. If it works it is still possible the signal from the heater controls is bad and telling it to shut off. Then you would have to find out why there is no signal when you turn the controlls to max heat.

    Good Luck
  • bear95bear95 Posts: 1
    #28 of 135 Too much heat! by focker1993
    Jul 21, 2007 (12:50 pm)
    I have a 1999 Chevy Blazer with the climate control. The problem is with my heat, it never stops. It constantly blows heat out of the vents. I can still change the direction ( defrost, floor, vents) and the speed of the blower, but cannot shut it off. The AC will not come on, the light comes on, but never any cold air, which I am thinking that it has something to do with this. I am looking for any suggestions please. It is hot outside and is unbearable sometimes to drive. Thank you very much

    Any help to share a solution to this posting? Thank you so much
  • pokey164pokey164 Posts: 1
    I have a 98 blazer and have no a/c dont know where to start
  • hewybohewybo Posts: 10
    my 95 blazer overheated today -got it home -filled with water -fine, no leaks. turned on a/c compressor,; within 2-3 minutes, sprang a leak. cannot find source, but it's dripping down on right side of bell housing area ( i think). the a/c condenser and heater core are separate, right? why a WATER leak when running a/c?????
  • What are the best replacement wiper blades for our vehicle?
  • duntovduntov Posts: 133
    Original equipment
    AC Delco 8-2162 (GM-89000993)
    16"insert with steel frame.
    RH and LH wiper.

    The have the AC Delco logo faintly printed on each blade to keep your Chevy all GM.
  • This problem is caused by an Electrically Operated Temp/Blend door that is controlled by the Tempature dial on LT models with "Auto Climate Control". (If yours has a temp control dial with numbers from 65 to 85) Anyway this door is controlled by an electric motor that opens and closes the door to vary the temperature. This motor Is called the Heater & A/C Blend Door Actuator. Its Part Number is (Dorman 604-106) This motor can be replaced by dropping down the Glove Box, and reaching through. Its right on top of the heater box. The motor is expensive - around $100 - $120. That should fix your problem.
    Scott - ASE Master Mechanic
  • I have a 2000 Blazer. The fan may or may not run. When it does run, the air temp is ok and heats the vehical and /or defrost the windsheild just fine. The controls check out ok. I think it is the vacuum system but I have no idea where to start, Any ideas?


  • John,

    I am working through some issues with my '99 Blazer. One thing I do know is the fan won't come on at all until there is hot water (anti-freeze) coming through the heater core. This is a built in function to prevent the system from pumping cold air into the cabin. You say that when it does turn on it works just fine. Perhaps that is the situation you are experiencing. Start your truck and let the engine come up to heat and see if your fan turns on.

  • I have the exact same issue with my '99 Blazer. I'm glad to hear there is someone else having this issue. Maybe now we can work on it together to resolve.
    If you have resolved since you posted perhaps you would be willing to share your experience with the rest of us.
  • I have a 98 Blazer with Automatic Climate Control, It had started out as a problem of no heat. Then we replaced the Control Module and that gave a little bit of heat being blown, only issue was the blower motor wouldn't turn off until you pulled the fuse.

    That lasted for maybe 20 minutes and then blower motor stopped again, this lead to us replacing the blower motor. With this it still will not turn off even with the engine off.

    The speed control knob on the dash isn't functioning the way it should, you can turn it all the way to off and still would be blowing full speed.

    So I don't know if this would be the issue and would resolve these problems. Just trying to look for some solutions as its pretty cold here and having to pop the hood to take out fuse all the time is less than ideal.

    Any help would be greatly appreciated, Thanks!
  • geno69geno69 Posts: 1
    My actuators look to be all working, just no air comes out on the floor. when you select the floor the air comes out defrost area.
  • jlflemmonsjlflemmons Posts: 2,242
    edited February 2012
    Oh, I have seen this one before, several times. The vacuum line that runs from the intake manifold to the vacuum resevoir in the drivers side front fender is rotted/leaking. It runs from the drivers side (left bank) of the intake manifold on the engine to a "tee" near the power brake vacuum booster. Check all the hoses and replace them if rotten. Actually, just replace them all because if some are bad, all will be close to bad.

    In the case of a vacuum loss, the directional damper will not move correctly.

    Will cost about $3 in vacuum line and takes about 15 minutes.
  • bdean8183bdean8183 Posts: 1
    edited February 2012
    I have a 99 Blazer with the auto climate control. About a month ago the blower motor would come on sometimes and sometimes it wouldn't. Seems like in the morning when it was cold it wouldn't come on but in the evening when it was warm it would. When it would come on everything would work great. It finally got to where it wouldn't come on at all so I wired it to the battery and ran a switch in the cab so I could just turn it on and off so I wouldn't freeze. When I flip the switch for the blower it blows strong but no matter what I turn the temperature to it blows hot air and cold air. What I mean is, it will blow extremely hot air for about 5 seconds then it will blow cold air for about 5 seconds. I can hear something in the dash making a clicking and whining noise now. I didn't notice this until I wired the blower to the battery. Before I wired the blower straight to the battery, I measured the voltage at the plug that plugs into the module. I've got 12 volts between the orange and black wire and 12 volts between the black/white and black wire. I also measured the purple and black wires that come out of the module and go into the blower motor. I've only got .0443 volts at those wires. I got another module out of a junk yard and it gives the same measurements so I don't know if I've got two bad modules or this just isn't my problem. Any help would be greatly appreciated because I am stumped.
  • I have a 1998 Chevy Blazer ST-10. Recently, the fan decided it was only going to come on sometimes. It will come on when it's freezing cold outside. I've pulled fuses reset the computer by disconnecting the battery. The heat is on, but the fan will not kick on. It doesn't matter if it's on A/C, defrost, or heat. As well, when it does decide to come on, it will not blow on the floor. We're in the middle of a winter storm right now in Northern Michigan, and I'd really like to have my heat back without paying an arm and a leg.
  • hi ive been working on tis right now found out there is a line that goes into the fender..see if that has fallen off..its very small and u need a mirror to see it,when that's off it defaults to defrost and vents only.
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