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Thread: Stupid Q on vent fan

  1. #1
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    Stupid Q on vent fan

    On a recent trip, I found that my vent/AC fan only ran on 4. I pretty much always have it on 4 because AC. I do want it to work, so I removed the resistor and found that the electrical plug was really crusty. I cleaned all the spades and put some dielectric grease on it and put it back. Now the fan blows hard on 4. Alittle less on 3. Less than that on 2, but it doesn't blow at all on 1 or 0.

    I assume it shouldn't blow on 0, but what about 1? My friend said that 0 shuts the vent door and 1 opens it, but doesn't run the motor. (You will get air if the car is moving.) He said all you have is three speeds for the fan. (2,3,4)

    I can live with this. I probably never use 1 anyways, but I want to fix it if it's broke. Is that how they all work?

  2. #2
    Senior Member Bitsyncmaster's Avatar
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    You should have 4 speeds. Three run through resistors and one is full voltage. It may be your fan speed switch is broken, the lowest resistor is open or the wire to it is broken.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #3
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    Quote Originally Posted by Helirich View Post
    On a recent trip, I found that my vent/AC fan only ran on 4. I pretty much always have it on 4 because AC. I do want it to work, so I removed the resistor and found that the electrical plug was really crusty. I cleaned all the spades and put some dielectric grease on it and put it back. Now the fan blows hard on 4. Alittle less on 3. Less than that on 2, but it doesn't blow at all on 1 or 0.

    I assume it shouldn't blow on 0, but what about 1? My friend said that 0 shuts the vent door and 1 opens it, but doesn't run the motor. (You will get air if the car is moving.) He said all you have is three speeds for the fan. (2,3,4)

    I can live with this. I probably never use 1 anyways, but I want to fix it if it's broke. Is that how they all work?
    They fail over time and are stupid cheap to replace. Just replace it along with the cage.

  4. #4
    Senior Member Rich's Avatar
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    Quote Originally Posted by Helirich View Post
    I assume it shouldn't blow on 0, but what about 1? My friend said that 0 shuts the vent door and 1 opens it, but doesn't run the motor. (You will get air if the car is moving.) He said all you have is three speeds for the fan. (2,3,4)

    I can live with this. I probably never use 1 anyways, but I want to fix it if it's broke. Is that how they all work?
    Your friend misinformed you. Both of the posts above are correct and here is the rest of it.

    Speed 1: has no effect on any of the HVAC doors. It will run the fan at lowest of the 4 speeds.
    Speed 0: has no effect on doors. Air will flow (through the non-driven fan cage) into the HVAC box if the car is moving and the mode switch isn't turned off. The air will come out wherever the mode switch tells it to, same as with the fan running.

    Only the mode switch moves any of the doors.

    N:01:01 to N:01:09 of the Workshop Manual
    Last edited by Rich; 08-03-2021 at 07:25 PM.
    March '81, 5-speed, black interior

  5. #5
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    Quote Originally Posted by MrChocky View Post
    They fail over time and are stupid cheap to replace. Just replace it along with the cage.
    Cage?

  6. #6
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    Quote Originally Posted by Helirich View Post
    Cage?
    The cylindrical blade mechanism attached to the blower motor is sometimes referred to as a cage.

  7. #7
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    Quote Originally Posted by MrChocky View Post
    They fail over time and are stupid cheap to replace. Just replace it along with the cage.
    Quote Originally Posted by CFI View Post
    The cylindrical blade mechanism attached to the blower motor is sometimes referred to as a cage.
    Chocky, is that what you were referring to? If so, are you saying to replace the motor. I have all ready removed the motor and cleaned/oiled it up months ago. It works great. I thought you were saying to replace the switch. (I think it might be the culprit.)

  8. #8
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    My VIN:    Yes.

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    For reference, this part is a match:

    https://www.rockauto.com/en/parts/vd...AKnKbLC9gZrhiU

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