Question about 2004 Chevrolet Blazer

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No floor heat

I have a problem with the heat in my 2004 Blazer. When I trun the control to heat (floor), the defrost (windshield) goes on. There is no heat on the floor and I can hear the defrost working (you know the sound it makes). The heat works fine otherwise but my feet are freezing off! Any ideas? Thanks.

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  • Panda5 Mar 04, 2009

    I have no aptitude for working on vehicles. I am not mechanically inclined. I have not looked under the dash because I do not know what to look for. I cannot look at the present time as I am at work. If it is a cable or a vacuum, what should happen when the knob is turned? Thanks for your help.

  • Anonymous Mar 16, 2009

    Plus balls.

  • Richard Scordino May 11, 2010

    That function is controlled either by a vaccuum motor or cable. look under dash and see what's not moving when it should.



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Many vehicles have a vacuum actuated valve (or flap) internal to the console vent plumbing. The vaccum line going to this valve/vac solenoid may be bad, unhooked or not functioning. In GM products, IIRC, the vac lines inside the vehicle are made of hard plastic, off-white in color (some have a slight green tinge) and are not easily flexible.

Check down under the dash where the floor output is and see if you see some of the plumbing of which I write. Then check to see if there are any loose lines, etc.

Posted on Mar 04, 2009

  • Rob
    Rob Mar 04, 2009

    fan on medium... move selector from def to floor setting... you should here something either or other noise behind or below the dash when you move the selector as the various flaps move in the heater plumbing to redirect the air flow.



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Posted on Jan 02, 2017

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SOURCE: How can I locate the blend door for the heater/defroster

you have a bad control switch.

Posted on Mar 05, 2009

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Usually a sign the blend door is not working under the dash. The blend doors direct air thru the vents and the heater core.

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Where is the windshield washer motor located? Is it near the heater motor? I had mine fixed and now the heat comes out of the dash for the defroster

Windshield Washer Pump Removal & Installation To Remove:
  1. Remove the air cleaner assembly.
  2. Remove the bolts. windwash.gif

  3. Position the pump and reservoir aside.
  4. Disconnect the electrical connectors.
  5. Disconnect the washer hose.
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Windshield washer solution contains methanol which is poisonous. Observe all cautions and warnings indicated on label of washer solution container.
NOTE: Windshield washer fluid should be collected in a container after the windshield washer hose is disconnected.
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The windshield wiper fluid pump is located in the tank which is not in the heater motor or defroster area in the dash.

The defroster/heat control door is located in the dash board area:

Air Door Actuators, Cables or Motors Removal & Installation Air Inlet Door Vacuum Control Motor To Remove:
  1. Remove the instrument panel lower insulator cover.
  2. Disconnect the vacuum connector.
  3. Remove the control arm clip and the spring.
  4. Remove the nuts and the air inlet door vacuum control motor.
Air inlet door vacuum motor mounting screws for-10-00-245.gif

To Install:
  1. Install the vacuum motor on the mounting bracket.
  2. Connect the control arm and spring.
  3. Connect the vacuum hose to the vacuum motor.
  4. Install the lower instrument panel lower cover.
Floor Defrost Door Vacuum Control Motor To Remove:
  1. Disconnect the negative battery cable.
  2. Remove the left lower dash insulator panel and disconnect the lamp.
  3. Remove the two pin-type retainers and remove the fill panel.
  4. Remove the DLC mounting screws.
  5. Detach the vacuum line.
  6. Remove the lighting module.
  7. Remove the screws and the bracket.
  8. Remove the floor/defrost door vacuum control motor.
Floor/Defrost vacuum motor mounting screws for-10-00-246.gif

To Install:
  1. Connect the vacuum lines and install the floor/defrost vacuum motor.
  2. Install the bracket and lighting control module.
  3. Install the DLC bracket and mounting screws.
  4. Install the fill panel.
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Panel Door Vacuum Control Motor To Remove:
  1. Remove the instrument panel.
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To Install:
  1. Install the panel door vacuum motor.
  2. Connect the vacuum line to the panel door motor.
  3. Reach through the opening and install the pin to the linkage.
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Jan 19, 2011 | 2003 Mercury Grand Marquis

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My air conditioner compressor comes on when i turn the dial to windshield/floor and goes off when i switch it to floor.

Do you mean the defrost position? Cause if so, that's what it should do. It's designed to come on for defrost to take the moisture off the glass in that setting and when you turn it to the floor setting, it turn's off unless you push the a/c on/off button to command it back on.

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Jan 03, 2010 | 1999 Chevrolet Blazer

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2004 Pontiac Montana blows cold air in defrost

There is a mix damper inside your duct that controls the heat over heater core and ac evaporator that to your floor and one to your defrost. it is probable an electric actuator, that is not functioning properly. If yu can locate it and manually move it, you might have to remove the actuator motor first, you should be able to figure out your problem, I hope this helps! merry Christmas!

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1998 Blazer, no heat to floor

Mine did the same thing. Has there been an accident where there may be glass that fell behind holding the shield door shut? If not it's the shield itself that is under the dash and you have to tear the dash apart to get to it. The shield is stuck shut on you and that is why there is no floor heat.

Nov 21, 2008 | 1999 Chevrolet Blazer

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