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  1. #1

    Question A/C Fan speed not working...

    Actually, setting 5 IS working, just not 1-4. The AC will blow cold on 5, and there is NOTHING on the other settings. When we got this vehicle back in 2007, I did notice a continual problem of setting 1 on fan, the air just didn't blow much unless the truck was moving. Then, last year, there was this little mouse squeak noise from the area to the left and under the steering wheel dash side. It'd do it every, oh, 11 seconds as a rhythm. I was wondering what that forebode. Perhaps now I know.SO.....I know little to bubkus about this, so help me out, please. Fan only blows on 5, dead on 1-4. AC works. Chkd the AC fuse BEFORE I realized that 5 worked ok.What might this be?Thanks from a newbie!Hil

  2. #2


    Tell me what you have for a truck is a help, but I can guess what the problem is, based upon your description.

    You have a manual control HVAC (as opposed to an auto unit). The manual units use a speed control resistor pac to control blower fan speed. Depends upon the truck, but this resistor pac is usually mounted on, or near, the blower motor. Again, depending upon the truck, this blower motor may be mounted below (behind) the glove box door.

    This is a very common problem, you must replace the blower motor resistor assembly(the resistor pac). Remove the resistor assembly and take it with you to the parts store. Also, check the condition of the wires and the connector as you may require a new connector and pig-tail.

    Also note, some of the new resistor assemblies no longer have the connector, it may be sold with just a pig-tail that needs to be soldiered into the wiring.

    You may still have a blown fuse. Some of the HVAC control units have one fuse for speed #5 and a 2nd fuse for speeds 1 - 4.
    Last edited by RayVoy; 07-26-2012 at 06:05 PM.

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  3. #3


    Hi Ray,Thanks. It is an '02 with manual adjust air (no fancy stuff in the LS, huh?). How difficult a project will this be? Where is the blower motor located? How much would a mechanic charge me to do this if I feel we can't?ThanksHil

  4. #4


    On a scale of 10, it's a 2. Look under the glove box, turn the blower on and listen to where the noise id coming from.

    BTW, LS stands for "less Stuff". hahahaha

    And hey, between you and me (and any one reading this thread), I like the manual stuff. Easy to fix, easy to use.

    You find the motor, and we can help you change it.

    I just checked your profile, your truck is a Trailblazer (I had an Envoy SLE (Same Less Equipment)) the blower is under the glove box. Just remove the knee bolister trim below the box and you can see it. The resistor pac is mounted to the blower motor.

    The fuse that handles 1 thru 4 is # 44 in the fuse panel under the rear seat.
    Last edited by RayVoy; 07-26-2012 at 06:22 PM.

  5. #5


    Here's a Diagram, of the 2002" Trailblazer the A/C...Heater Module......Number #12 in the Diagram, is the Blower Motor Resistor, that RayVoy mentioned, hopefully the diagram will be able to help you out....


    5.3 l 3.73 l G80

  6. #6


    Thanks Heartbeat

  7. #7


    Quote Originally Posted by RayVoy View Post
    Thanks Heartbeat

    I didn't do anything, You gave the OP Excellent Advice As You Always Do......
    Last edited by 99'HEARTBEAT; 05-16-2013 at 10:20 AM.

  8. #8


    Quote Originally Posted by 99'HEARTBEAT View Post
    I didn't do anything, You give the OP Excellent Advice As You Always Do......
    Exploded diagrams can be a big help, might also scare the op away

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