Can anyone help me with some wiring?

Discussion in 'Troubleshooting & Diagnosis' started by BradM, Feb 11, 2018.

  1. BradM

    BradM New Member

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    Feb 11, 2017
    1978 Z28.......need help with the correct location of where these wires from the relay are supposed to go. Someone has cut and added things and I can not get the new heater motor to work. Motor was tested before install and worked. This larger tan wire on end of relay has been cut and a wire added to it. It was under the dash and cut. It DOES go hot when the fan switch goes on, but I still can't find issue. There are two smaller Black wires on heater motor....Hot and Grnd, I'd guess. Hot wire goes from motor to relay, then back out of same relay terminal and back into harness. If you run 12v to that wire, the motor still won't run....We need help, please.
    Thank you!
    P_20180211_150940.jpg P_20180210_153612.jpg
     
  2. HOGDADDY

    HOGDADDY Veteran Member

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    Jun 8, 2005
    Birmingham,Alabama
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  3. BradM

    BradM New Member

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    Feb 11, 2017
    I was thinking the same, but the blower motor already has two wires connected to it......surely it doesn't use two Black wires for Grnd and this Tan wire for hot.......? I'm confused......
     
  4. HOGDADDY

    HOGDADDY Veteran Member

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    Jun 8, 2005
    Birmingham,Alabama
    I think it might be related to blower motor resistor that controls the fan speeds. That plug is underneath the heater box.
     
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  5. dale68z

    dale68z Veteran Member

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    May 14, 2009
    Glendale Arizona
    my opinion, sounds like the black wire just needs to be grounded. Usually it is grounded at the firewall just to the drivers side of the AC case. 2 black wires are ground one of them should be attached to the blower, red is b+, blue goes to the blower switch + when in high speed, other blue should go to the blower resistor that is attached to the AC case. The relay should be screwed to the AC case also, real close to the resistor assy
     
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  6. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

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    Jan 10, 2003
    USA
    Look at the diagram. On the left just under center its exactly what you have.[​IMG]
     
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  7. BradM

    BradM New Member

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    Feb 11, 2017
    I don't understand what that #63 circle is, that the Tan wire goes to from relay. That's the wire that was cut and laying there.. HVAC relay wiring..PNG
     
  8. BradM

    BradM New Member

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    Feb 11, 2017
    Also......that double Black wire going back to the blower motor, shows Grnd, when I touch a powerprobe to it.......That has thrown me, since there is nowhere to hook a Hot, if both of those Black are a Grnd.......
     
  9. 80sz

    80sz Veteran Member

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    Feb 2, 2014
    Buffalo,n.y.
    The 63 is the hot feed attached to the blower motor from relay.
     
  10. BradM

    BradM New Member

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    Feb 11, 2017
    Thank you. So, these Blacks are going to Grnd and what is #150? HVAC relay wiring..PNG
     

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