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heater motor about to push me over the edge, wiring guru's help

Discussion in 'The Garage' started by milspecjimmy, Jan 1, 2003.

  1. milspecjimmy

    milspecjimmy 1/2 ton status

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    heater motor about to push me over the edge, wiring guru\'s help

    ok, so far i have replaced the switch, the relay, and the motor. what it does, it will work on low, med, high, and not max. before todays surgery it would only work on low, med, go back to low when in the high position, and pop the fuse on max. today i jumper it at the relay harness with a full 12v and nothing happend, and my dad noticed aspark at the ground wire. so i took it all out of the truck, ground a spot off and soldered a ground wire directly to the case. i tested it with 12v and it turned up to speed really fast and worked fine. so i reinstalled it, and now it works on low, med, and high. still no max. however it doesnt pop the fuse on max any more. it does dim the dash lights when the key is on and engine not running when i put it on max, but it only turns at the low speed in the max position. so what can be wrong? any ideas? please help!!
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    My blazer did the exact same thing, but when I replaced my switch it worked fine. I would double check the tightness of the wiring on the switch and maybe also take a good look at the switch itself. ( I know you said it is new, but that doesn't mean anything these days. )
     
  3. tori89k5

    tori89k5 1/2 ton status

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    Finally we get to see a pic of your rig Scott ! Looks good. Id like to see more of what ive heard so much about. You got a album or anything on here ? /forums/images/graemlins/thumb.gif
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    On the highest setting, the swtich is supposed to complete the circuit that energizes the coil in the relay. This will change the source of power for the blower motor. When the relay is off, power is routed through one side of the relay contacts and the resistor pack. When the relay is on, power is routed through the other side of the relay contacts and a direct 12 volt feed from the power stud mounted on the firewall. There's a heavy wire that runs from that stud, through an inline fuse, to the relay.

    I'd start with the power for the relay coil and see if it's getting power on the highest setting. If not, then trace back through the wiring to the switch. If it is, then the output side of the relay should have 12 volts on it when it's on. If it doesn't, then the relay itself is defective.
     
  5. milspecjimmy

    milspecjimmy 1/2 ton status

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    thanks harry ill check that out
     
  6. ntaj*ep

    ntaj*ep 1/2 ton status

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    What Harry said /forums/images/graemlins/thumb.gif
     
  7. jjlaughner

    jjlaughner 3/4 ton status

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    Same thing here! POP's went out and looked it over for 2 minutes (after I spent several hours cleaning, replacing parts), he found that the power wire in the connector to the relay was burnt up and was not making contact with the relay. 2 more minutes with a tiny screw driver and WOW HEAT! ON MAX EVEN! /forums/images/graemlins/thumb.gif
    I drove for 2 years with no heat because of a damn wire not making contact /forums/images/graemlins/tongue.gif /forums/images/graemlins/deal.gif /forums/images/graemlins/rolleyes.gif
     
  8. milspecjimmy

    milspecjimmy 1/2 ton status

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    yeah the plug on mine is a little shady looking. i am going to cut the plug out and go direct on all the connectors
     
  9. milspecjimmy

    milspecjimmy 1/2 ton status

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    Re: heater motor about to push me over the edge, wiring guru\'s help

    well i went and cut off the plug, put female connectors on all of the wires and pluged them directly onto the blades sticking out of the relay, now i have low, med, and high. still no max. tomorrow i am going to turn the key off, and put the switch in the max position and unplug the hot lead from the blower motor, then check the ohm load to see if it may have a short in it, if it does ill have to trace it back to see where its grounding out. thanks for the help and ill keep you posted
     

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