Outside heat pump not running at all

Discussion in 'HVAC Heating & Cooling' started by Tom M. P., Jan 10, 2010.

  1. Tom M. P.

    Tom M. P. New Member

    Messages:
    3
    Location:
    Tennessee
    I live in Tennessee and we are getting temps in the 20's. I have two heat pumps, one for 1st floor and one for 2nd floor. The 1st floor unit seems to run fine, the 2nd floor outside unit does not run at all. It has been this way for a few weeks. On this unit the inside air handler and aux elec. heat is all that is working right now. I would like to check whatever I can prior to calling my service co. Any Ideas? Thanks
  2. SteveW

    SteveW DIY Senior Member

    Messages:
    1,053
    Location:
    Omaha, NE
    It depends on where the "balance point" is set.

    That's the temperature at which the system switches from heat pump to aux heat.

    On my system, we have it set at 20 degrees F. I have seen other recommendations to set the balance point in the 30's, however. Depends on your local utility rates.
  3. Tom M. P.

    Tom M. P. New Member

    Messages:
    3
    Location:
    Tennessee
    It appears the unit in question is just dead, it does nothing. The unit next to it runs and stops as it maintains temperature. What should I check - I have voltage tester etc. There is some sort of blade type cut out at outside wall near unit and the breakers inside are not tripped.
  4. SteveW

    SteveW DIY Senior Member

    Messages:
    1,053
    Location:
    Omaha, NE
    Do you have a separate thermostat for each unit?

    If so, first place I'd start is looking at how it is set up, to make sure it's actually calling for heat pump operation.
  5. Tom M. P.

    Tom M. P. New Member

    Messages:
    3
    Location:
    Tennessee
    It has its own tstat and it was the new programmable tstat I installed. It has 2 Y terminals on it and I put the wire to the wrong y terminal. Works fine now - Thanks for the help
  6. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Jump the heat pump at it's terminals to give it a call for heat and see what happens.
  7. gator37

    gator37 Retired prof. engr.

    Messages:
    108
    Location:
    Alabama
    This is what I would check before I called a service person

    Don't know if these new units still have what I am going to say but the first thing I would check is to make sure you are getting power to the unit.

    Than I would check the starter relay to insure it is providing power to the compressor first by the thermostat call for the unit to come on which should activate the relay providing power to the compressor. If not by manually activating the starter relay to see if the compressor starts.

    If that doesn't work I would turn off the power and pull the three leads off the compressor and check for continuity between leads on the compressor with an ohm meter. Should read something. If no reading the compressor has an open winding....
    I would also check the leads to see if you have any shorted lines in the compressor by checking resistance between that and the compressor can.
    Should get no reading on the ohm meter. If reading the compressor winding is shorted.
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