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Compressor and Blower Fan both don't start up on HVAC

lbeachmike
lbeachmike Member Posts: 215
in THE MAIN WALL

I have a Lennox Model XC16-024-230-02 condenser and CBX27UH-036-230-6-02 blower unit. When the thermostat is calling for cooling, the fan on the condenser turns on but the compressor does not. I can hear the compressor humming but not starting up. At the same time, the blower motor does not start up (but also seems to hum). If I turn the thermostat to Fan On, the blower fan also does not start up.

I thought this might be one leg of power failed, but the condenser and blower units are on two totally different double-breakers.

Any ideas?

Comments

  • mattmia2
    mattmia2 Member Posts: 13,862
    edited August 21

    did you check voltage between lines and between each line and neutral?

    Are you sure the compressor hasn't been not working for a while and you didn't just notice it until the indoor blower stopped?

    is this a single phase 120/240 v service?

  • lbeachmike
    lbeachmike Member Posts: 215
    https://forum.heatinghelp.com/discussion/comment/1862940#Comment_1862940

    I am certain the compressor has been working. We have two units in our house - this unit is for the upstairs. We only use it at night when we go up to sleep in the upstairs bedroom. If the compressor was not working, it would have been super-hot and super-stuffy. The cooling has been normal. As you know, the compressor also has a very distinct sound when on. It would have been very noticeable in both regards.

    I have not checked any voltages anywhere yet. I was going to check voltage coming into the contactor to make sure I see 240V there. But it also feels rather pointless, given that the blower does not turn on even by turning on only the fan.

    As far as I am aware, I have single phase 120/240 service.

  • pecmsg
    pecmsg Member Posts: 6,388

    If your concerned dealing with high voltages call a contractor

  • neilc
    neilc Member Posts: 3,038

    could be caps, could be motors, could be contactors,

    your meter knows,

    known to beat dead horses
  • HVACNUT
    HVACNUT Member Posts: 6,952

    It seems odd that both the compressor and indoor blower motor failed at the same time. Definitely check the voltage, but the downstairs system is fine, so maybe caps on both? Any surges in your area?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 10,878

    I'm betting on the Capacitors. here is a way to check them without a Capacitor tester, all you need is a volt meter with an amp probe.

    https://www.youtube.com/watch?v=XRYlmMtrY_A

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,382

    Harbor Freight has chepo meters that include capacitor testing for about $20.

    My cousin goes to FLA in the winter and forgot to bring the meter I gave him. Got one at HF for about $20

  • mattmia2
    mattmia2 Member Posts: 13,862

    the meters i have had with capacitance meters built in have only read to like 1000 pf.

  • 109A_5
    109A_5 Member Posts: 2,581

    Weird or odd behavior, always check the power first under load.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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