Blower motor only goes one speed.

Discussion in 'GM Electrical Tech' started by Jalaube, Jun 3, 2013.

  1. Jalaube

    Jalaube New Member

    The blower motor in my 1977 Chevy C30 flatbed truck only goes one speed (it is slow) it doesn't change speeds whatsoever when i move the switch and it runs even while the ac is switched to off, if I bypass the relay it goes really fast so I'm assuming the problem is the relay.

    Any ideas on what might be the problem before I go out and buy a relay.
    Last edited: Jun 3, 2013
  2. mfleetwood

    mfleetwood Epic Member 5+ Years ROTM Winner 5000 Posts

    Welcome to the Club!!!

    I moved your thread here as this will help in getting more opinions/responses than the Member Intro section.

    Sorry, I do not know the answer, but someone should be along shortly who can help...

    Good Luck!
  3. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    Ordinarily, my gut reaction would be to say blower relay, but I'm not sure that's the case in this situation. When the blower switch is off, the blower should stop. Because it's not, I'm suspecting the blower speed switch in the cab, or a short in the wiring somewhere that's allowing 12 volts onto a blower control wire. Pull out your multimeter and probe around using the Haynes manual for determining what wire's for what.
  4. Jalaube

    Jalaube New Member

    image.jpg This is a pic of the back of the switch it looks like there is a wire missing don't know if that's the problem or what color wire would go there. (This is a pic taken from the bottom side.

    - - - Updated - - -

    It was the switch I took it out and tested it with an ohm meter and all of the settings showed no connection but I manually connected the terminals on the connector the switch went into and I could change the blower motor from low to medium to high and figured out that the blower is always supposed to be on (about half the speed of low)

    Thanks for the help.

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