Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

finicky fan

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by coolhandluke, Jul 10, 2002.

  1. coolhandluke

    coolhandluke 1/2 ton status

    Joined:
    Oct 23, 2001
    Posts:
    116
    Likes Received:
    0
    Location:
    Dallas Texas
    Ok guys, I have a problem with my ac/heater fan. It is finicky. At first I thought I had a short, it would come off and on randomly. Well, since then I've changed my mind, and I don't know what the heck the problem is. Here's the deal, once it's going, it's fine, no bumps, or wiggling, etc, will turn it off. However, about 1/4 of the time, when it stops for any reason, it won't come back on when you start it back up. At least, not immediately, if you hit a big bump, etc, then sometimes it will start back up. It's like it the motor get's "stuck" and can't move past that place on it's own. Has anyone had this happen to them? any suggestions? I'm checking for shorts tonight, but am pretty sure that it's going to have good power, yet still not be turning. Is there anything that can be done to fix it, or do I have to get a new fan motor?
     
  2. TopOff

    TopOff 1/2 ton status

    Joined:
    Jan 16, 2002
    Posts:
    1,760
    Likes Received:
    0
    Location:
    Folsom, ca
    My vote is to check all wiring connections, especially the negative wire going to the vent/cowl piece where the AC/Heater motor mounts. This negative can be corroded causing these symptoms.

    I had to replace my motor as the bushings were squealling really bad. The motor was only ~$26.00 new!

    Good luck.
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,173
    Likes Received:
    1,385
    Location:
    E-town baby!
    Here's another vote for that ground wire. Mine was corroded and did exactly the same thing.

    Rene
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,979
    Likes Received:
    189
    Location:
    Roy WA
    Check connections, but sounds like the same thing that happens with starters, where they might work the first time you crank it, but it ends up on a "dead" spot for the next time you try, and you end up with an inoperative starter.

    If its not the wiring connections externally, try tapping the case of the fan with a hammer while its turned on, but not working, and see if that fixes it...if it turns on, I'd replace the fan motor.
     
  5. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    I've had two other things cause this behavior. A bad motor (brushes were shot) and a bad blower motor relay. To bypass the relay, connect a 12 volt source directly to the input of the fan motor and see if it runs all the time. If so, then it's probably the relay. The relay should be on the firewall, near the a/c evaporator. I've had the relay fail on several different GM vehicles over the years. /forums/images/icons/mad.gif Only had a motor fail once.
     

Share This Page