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Low Air Flow in Front Heater

Discussion in 'General Chevy & GM Tech Questions' started by Montanan, Feb 9, 2013.

  1. Montanan

    Montanan New Member

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    Hello,

    I am new here, signing up to figure out what I did wrong in repairing the heating on my 1996 Suburban C1500. I am scratching my head, please help.

    My fan blower was making a nasty screeching noise in cold weather, plus the medium 1 fan speed setting was not working. I took out the blower motor, lubricated it, cleaned out the area around the blower motor (pretty clean really for a 16 year old car). Blower works fine now, no noise. Then I changed the A/C & heater fan control switch behind the dash, now all fan speed settings work. So far so good.

    Now with everything put back in place the air flow through any of the vents is not a fraction of what is was before! I checked the air-flow direction actuator: it seems to work, a bit comes out of the defroster when directed there, and also from the other outlets. The blend door also seems to work: I can adjust the temperature of the bit of air air coming out. I took off the cover underneath the heater core (not too hard if done with a very thin 1/4 inch ratchet), and the inside was super clean. The flap door for inside circulation (close to the blower motor) seems to be working too. So what the hell could possibly be restricting the air flow? Is there another flap door I don't know of? Is there a flap door in the air flow direction actuator that could be stuck?

    I ordered a replacement for the A/C, heater, blender control console, since that seems to fail often, but I'd rather not put in a new $ 140 part if that is not the culprit.

    Any suggestions from people who have more experience with this than I do -- this is the first time I ever did anything with the heating system.

    Thanks!
    #1
  2. RayVoy

    RayVoy Active Member

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    Without being there to listen, I'm thinking the blower motor is the problem. It noisy and you lubed it. Did you take it apart to do this?
    #2
  3. Montanan

    Montanan New Member

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    Thanks Ray,

    Without taking it apart I sprayed a bit of 4WD at the two endpoints of the shaft of the blower motor, using a long flexible plastic nozzle. The fan seems to be blowing full blast to me, but of course I've never see it operate before the lubrication. Would be nice if that is the problem, because that motor is easy to replace. Any thoughts?

    Love that car! I have five kids and two dogs and we take it everywhere, skiing, hiking, camping.
    #3
  4. Conlan Rose

    Conlan Rose Super Moderator

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    Are you stating that air is coming out of all vent? This can usually be fixed by turning on the A/C. This will force the defroster door closed and only allow the front or foot vents to work. Try it a few times. Worked when it happened on my truck and has worked on others from this gen on the site.
    #4
  5. Montanan

    Montanan New Member

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    What I meant to say is that the air comes from any vent (floor, dashboard, window) that I direct it to, but only in a trickle. I tried the A/C remedy (thanks Conlan), but it did not work. I also replaced the fan motor (not very expensive really), but it makes no difference, same sound, same fan speed.

    So what else could be wrong? Something stuck in the flow direction actuator? Something a new A/C heater, fan, etc console could fix?

    Thanks again!
    #5
  6. Conlan Rose

    Conlan Rose Super Moderator

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    Is the fan speed selector working? If it is maybe the fan resistor is bad.

    - - - Updated - - -

    Realized I never told you how to test. There are two way that I see to be do able.

    Way one: if you have a friend with a GM truck from the same gen 95-98/99 test your controller in his truck if it works fine in the truck and controls all the speeds then the fan resistor is bad. If same thing that is happening in your truck happens in his then the controller is bad. You should also test if his works you system properly. Just make sure his works 100% first.

    Way two: buy new controller and resistor(to be safe) plug in new controller is everything works your set, YAY, if still same then replace resistor and test again. Make sure to test both units for functionality because if you original isn't the problem then why keep the new one just return it to refund your money.
    #6
  7. Montanan

    Montanan New Member

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    Yes, all four fan speeds work fine. Is there a flap door or similar in the part that directs the airflow to the different outlets? I have not found any drawings online. Thanks again.
    #7
  8. Conlan Rose

    Conlan Rose Super Moderator

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    No problem! Here's the best drawing I can get there are 2-3 direction doors I think. They also say their is an air filter part 33 I've never seen a replacement part for it tho.


    ac-heater-module-asm-tc0904501.png
    #8
  9. Jimdandy

    Jimdandy New Member

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    You obviously removed the entire blower assembly from the housing in order to lubricate it....did you reconnect the wires backwards? IIRC the Purple one is closest to the motor, while the black (ground) is further to the outside.
    #9
  10. Montanan

    Montanan New Member

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    Yes, you got it. I took it to my garage guy to ask, and he immediately suggested that. That was the solution. I had actually tried to reverse the wires, but they didn't fit easily and the colors did not match. I feel pretty stupid, but, hey you live and learn.

    Thanks!
    #10
  11. Jimdandy

    Jimdandy New Member

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    Glad that it was as easy as that. BTW, where did you get the exploded view of the HVAC assembly?
    #11
  12. Montanan

    Montanan New Member

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    One of the respondents put it online for me.
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