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Thread: Fan Relay

  1. #1

    Fan Relay

    I'm having trouble bypassing the fan relay on an 2007 american standard package unit. I replaced the old mtr with after market mtr, the factory mtr had a built in relay, the new mtr does not, the new mtr runs on cooling but does not run on heat so I tried to add a relay but cant figure out how to hook it up, here's what I've tried so far... 24v green wire from thermostat, and common wire off the 24v side on transformer to the 24 volt side on relay, then commom (white) off the fan mtr to the L1 on contactor, thenI ran a jumper from L2 to 3 on relay, then black (high speed) from the fan mtr to 5 on the relay, then push in contactor and indoor mtr doesnt run. then i can take the white (common) off the contactor to the common on the 35/5 copacitor, then take the (black) wire off the realy and connect it to L1 and then the fan will run on cool but not heat. hope that was detailed enough. Any help would be great thanks

  2. #2
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    There is not a motor made with a OEM internal relay. Post model and serial of said unit and what brand and type of motor you are trying to install. For now put down the tools and please step away from the RTU.

    In heat mode assuming it's a gas RTU the unit control board energizes the blower motor, the thermostat does not control blower function in heat.

  3. #3
    Join Date
    Jun 2004
    Posts
    854
    Sorry I got dizzy trying to follow that?

  4. #4
    Join Date
    Dec 2005
    Posts
    3,970
    Quote Originally Posted by aggiechillertech View Post
    There is not a motor made with a OEM internal relay. Post model and serial of said unit and what brand and type of motor you are trying to install. For now put down the tools and please step away from the RTU.

    In heat mode assuming it's a gas RTU the unit control board energizes the blower motor, the thermostat does not control blower function in heat.
    I've seen several blower motors recently that have a built in fan relay.

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