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Two speed fan motor

Generally speaking do multi-speed condensing fan motors act that same as a multi-speed blower motor? I came across a "two-speed" ICP condensing unit with a solid state outdoor fan control that would change speeds on the motor only. A common leg was switched through the PCB to power up low or high. I was befuddled because we use the "rescue"(*tm) motors that use different legs for different hp ratings. The existing motor dogtag only listed one rpm (840). The compressor is a scroll single speed. I think I can use a multispeed condensing motor and connect the proper speed taps and make sure that the PCB is only powering on hot terminal at a time. Yes??


  • Empire_2
    Empire_2 Member Posts: 2,343
    Rescue motors...

    They are nice when in a bind. Other than that I like to use suggested motors that are on the tag. The answer to you Q: is yes, but the cond fan in this case operates off of out door air temps depending on the age of your condenser. Is your solid state control a motor master or something like it? Or is it a standard fan cycling control?. I believe that it is not your common leg that changed to change the speed. If anything it was the hi/lo taps that actually switched on the 220vac circuit.

    What is your application? does it need the 2 speed taps? Generally the low speed will be rated at lower HP as you are seeing on the rescue motor, But aren't they expensive? Also, 840 with the ICP model,..?? is this a Heil or carrier? they are now both owned by the same company.

    Mike T.
  • rucomfy_2
    rucomfy_2 Member Posts: 10
    Thanks for the help....

    Motor is controlled via a PCB device with 24V power up with contactor hit from stat. It is a solid state device with no visible external sensors probably an on-board thermistor. The schematic shows a temp activated contact diagram with the relay contacts in the normally closed position for low speed. The PC device uses the switched leg of the 220V to power up either the hi or lo blower speed tap/leg. The other leg is on the common side of the contactor which would complete the 220V circuit to allow motor operation. This is newer 14SEER ICP unit. Not familiar with all the nuances of the controller but it is not a motor master or a low ambient kit. It may be specific to ICP models, have not seen it on Carrier/Bryant. Scheduled for CAC/BDP class later this month, I will check with my "Uncle Wayne". I am pretty sure that if I have a two speed motor if can use it. I would probably recommend a new PC because if it powers up two legs at once such an internal relay failure it would mimic a bad motor or kill it. Thank you for taking your time to respond to my questions.
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