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Heater fan speed control

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ftn96, Dec 27, 2000.

  1. ftn96

    ftn96 1/2 ton status

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    90 Jimmy)--- Fan motor now only works on high. Has anyone else experienced this ot something simular? Was wondering if I need to replace the fan motor, or if the switch is the problem and is it sererate from the motor. Just looking for a heads up before I go pulling things apart.

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  2. HarryH3

    HarryH3 1 ton status Author

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    The fan blower relay is the most likely culprit. It's mounted on the firewall and looks sorta like a horn relay. Around $10 at any auto parts store.

    <font color=black>HarryH3 - '75 K5</font color=black>
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  3. ftn96

    ftn96 1/2 ton status

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    Well, Hair-e, LOL, I'm sorry but Im lazy, so after I posted the message. I did a search and found that mudhog had the same problem as me, but he had explained the details more. I left out that I have to wiggle the switch and then the hi comes on, he said he had pulled the dash off and replaced the swithc itself and that did the trick. Any more input?

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  4. HarryH3

    HarryH3 1 ton status Author

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    If you can wiggle the switch and then the fan comes on then it sounds like the switch is a goner. I've never had the switch itself fail, on at least 10 different GM vehicles. I've had the relay fail on almost every one of them!

    <font color=black>HarryH3 - '75 K5</font color=black>
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  5. Channing74

    Channing74 Registered Member

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    Resistor could be the bad part also. Not a bad idea to change both the relay and the resistor. The resistor is located right by the blower motor. Default speed on the resistor is high as it uses resistance to regulate the voltage. I just looked this up in my mitchell on demand to verify.

    Bigger is Better [​IMG]
    Channing74
     
  6. Zepplin

    Zepplin 1/2 ton status

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    I have the same problem. I just put my order in for a new fan plower resistor. Which is loclated under the hood next to the blower motor. I couldn't find it at a parts store (its a 74) and had to go to the dealership. It will run me about $12.

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  7. ftn96

    ftn96 1/2 ton status

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    You see? Thats why I love this site. Thanks gents.
    I didn't even know there was a resistor.

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  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Well chalk up another one for a bad switch. I just did that about a month ago. Same deal, I only had high speed and would have to wiggle the switch, then it got to the point if I even touched the switch it would blow the fuse, I finally broke down and bought a switch.

    Rene

    [​IMG]
     
  9. ftn96

    ftn96 1/2 ton status

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    So you think I need the "switch" too?? tRusty, I have the exact same problem. Is it the switch or the "resistor"?
    I looked at Naponline, they have motors, switches and relays. All to do with the heater stuff.
    Which one do I get? The switch?

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  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I just did the switch, like you I didn't even know there was a resistor. Thats what fixed it for me.

    Rene

    [​IMG]
     
  11. ftn96

    ftn96 1/2 ton status

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    Cool, they have those at Napa. I dont like going to the dealer.
    Is it like Mudhog said, just that section of the dash off, pull the face back and whallahh? Unplug and replace.

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  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Yup, just don't pull to hard on the heater control bit, just enough to get to the switch.

    Rene

    [​IMG]
     
  13. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    well like trustyk5 i didnt even know about the resistor
    i just put in a new switch works great. now if i could only find the heater controller console i would be doing even better

    s.smith 77blazer lookin 4 mud
     
  14. Zepplin

    Zepplin 1/2 ton status

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    I also replaced the switch also because it somehow melted the plastic connector where it mounts behind the Heater/Defrost panel. But, this parts are cheap so might as well replace them as a pair, just in case.

    Communication Breakdown
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  15. ftn96

    ftn96 1/2 ton status

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    Thats cool. I'll get the switch and start the R&R and see what else is in there that might need replaced. I gotta do something, its either too hot or too cold, plus the damn duct work behind the dash doesn't fully work, it lets heat out of the dash vents when its on floor heat, and that crap blows right in my face. MAkes me very sleepy while driving. I would closed the little leuvers but they are all broken out on the drivers side.

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  16. k5king

    k5king 1/2 ton status

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    <font color=red>heat????</font color=red> what the hell is heat???

    ANYBODY LOSE THEIR JEEP????????[​IMG]
    I JUST FOUND ONE UNDER MY BLAZER!!!![​IMG]
    [​IMG][​IMG]
     
  17. ftn96

    ftn96 1/2 ton status

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    Dont know, Its been so long sinvce I've felt any.

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  18. ftn96

    ftn96 1/2 ton status

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    Re: Heater fan speed control (Plan B)

    Well, I replaced the fan switch, NO DICE!! Still doesn't work. Now it only comes on when ever it wants to.

    So should I replace the relay now or the resistors?

    Will work for parts, beer and sex.
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  19. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: Heater fan speed control (Plan B)

    So it does come on once in a while? I feel kind of stupid not mentioning the ground problem I had before my switch went [​IMG] your post just reminded me.
    On the blower motor there is a wire that attaches to one of the screws that holds the motor in. On mine it had corroded and I lost ground. I moved the wire to another screw, just make sure you clean the wire and the paint of off the motor housing.
    That worked for me, but it was quite a while ago which is why I forgot.

    Rene

    [​IMG]
     
  20. ftn96

    ftn96 1/2 ton status

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    Re: Heater fan speed control (Plan B)

    Well, for all who care. I took the fan motor out and hooked it up to a battery, NADA!!!! So I went to NAPA and got a new one, and $53.01 later, I put it in and whalla, I now have heat fan speed control. Thansk guys. Also in reguards to the resistors that you all talked about, I had no idea they even existed. But last night in the LMC catalog, I saw a picture of it and come to find out that it has been sitting right there in front of my face the whole time.
    But again thanks for all the help.

    Will work for parts, beer and sex.
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