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Freezing my Boys Off

Discussion in 'The Garage' started by Mudbug1979, Dec 13, 2005.

  1. Mudbug1979

    Mudbug1979 1/2 ton status

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    OK, My K5 gets a little cool when the heater won't blow on high. I have replaced the blower motor, dash switch, and the coil thingy in the evap box under the hood. The motor will work fine on 1-3, but when you switch to 4 it dies completely. Whats next, someone mentioned a blower motor relay, but I have no idea where that bad boy is. Help please....... Thanks.
     
  2. chevyjeff

    chevyjeff 1/2 ton status

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    blower motor relay is on the top of ac box. 4 wires in a rectangular type plug.
     
  3. K5er4Life

    K5er4Life 1/2 ton status

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    what temp thermostat you got in there? If your truck is running too cool then you wont get barely any heat in the cab. When you turn your heater on high like that all your doing is cooling down the coolant even more therefore on high thats why you get cooler air. I had this in my blazer and from what I remember I went from a ~170 to a 195 degree t-stat. That seemed to help alot, especially on high the air was much more warm. Ohh and that is providing that your heater core is allowing enough flow through it too. Which is another possibility.
     
  4. Mudbug1979

    Mudbug1979 1/2 ton status

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    I'm running a 195 degree, but the thermostat is working properly. The motor only runs on 1-3, not HIGH. I replaced that relay then, the only other thing I could be is the resistor on the front of the blower motor. If anyone else has any ideas it would be greatly apperciated.
     
  5. Mudbug1979

    Mudbug1979 1/2 ton status

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    Anyone?
     
  6. onlychevy6

    onlychevy6 1/2 ton status

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    at least you have a heater. mine does not work at all. Still trying to figure out the wiring. When i purchased mine the wiring was gone.
     
  7. GotLabs

    GotLabs 1/2 ton status GMOTM Winner

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    Have you checked the switch to make sure you are getting voltage on high? I have had switches go bad at one location only.
     
  8. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Yep, had that happen too.
     
  9. MTMike

    MTMike 1/2 ton status

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    Check the switch, and check to see that voltage is getting to the blower motor when it's on high. if it is, it's something at or in the blower motor, if not, check everything in between.

    Could it be a bad ground somewhere too?
     
  10. Mudbug1979

    Mudbug1979 1/2 ton status

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    Is there anyway that it could be the Resistor that is on the outside of the blower motor. I have changed the switch 3 times and still no high. I'm outta ideas, anyone else.
     
  11. diesel4me

    diesel4me 1 ton status Premium Member

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    maybe...resistor is easy to change at least...

    I'm not sure if the resistor is even "in the curcuit" on high speed or not..:confused:

    Here in MA,it gets so cold I use only "HI" or nothing at all--so if my truck had a dead resistor I wouldn't miss the other speeds...in fact,all GM trucks from 73-87 have a "continuous running blower" --that means its really "on" at "low" speed when the switch says "off"!...

    I learned this when my blower motor decided to sound like a seized bearing at 10 degrees one morning--scared the p*** outa me,I thought it was something serious!..had to put up with that chalk on the blackboard noise every cold morning until the blower motor heated up some--if I put it on high it would go away faster!--

    I drilled a small hole in the motor housing where the shaft is,so I could add a bit of oil..then I snipped off the wire that had power when it was on "off" that made it run constantly!;)

    Many of my trucks I just put a fused 12V hot wire from a toggle switch directly to the blower motor so it would only run on "high" speed..I found it wound out a bit faster that way..an A/C equipped blower motor has a bigger fan and spins much faster than a non A/C one,and they are a bolt in swap!..many GM car blowers are the same too..I usually swap one in on my trucks..nothing worse than an anemic heater in cold climates..:mad: :crazy:
     
  12. Mudbug1979

    Mudbug1979 1/2 ton status

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    Which wire should I hook up to a toggle switch so that I can turn it on high when ever I want???? Thanks.
     
  13. dave_90_blazer

    dave_90_blazer 1/2 ton status

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    make sure you have 12v to the relay with the key off(not sure which wire, probably a big red one...), if not, that is the problem
     
  14. diesel4me

    diesel4me 1 ton status Premium Member

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    heater switch by-pass

    Just use the wire coming directly out of the blower motor housing if you feel you must by-pass everything with a switch.(its sometimes a black wire,don't be fooled into thinking its a ground wire!--it plugs onto a "spade" connector sticking out of the motor housing--a rubber bootie is made onto the wire..sometimes the wire is orange too,its different on some years..

    Its nice to keep everything working the way it came from the factory though,if possible..its easy to replace the relay and resistor with new,or cheaper used junkyard parts if they are suspected of being defective..might go that route first!.

    I use toggle switches on my 20+ year old plow trucks--yours might be nicer and newer than mine,you might not want to go the "crude but effective" route on your truck.... :)
     

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