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Trane air handler cycling rapidly

Air handler on Trane heat pump will intermittently cycle on and off rapidly. It sounds as if the motor tries to start but can't then stops. At times, it will do this for minutes on end -- cycling on momentarily, then off for five or ten seconds, then do the same again. If I move the fan switch from Auto to On, the fan starts immediately and runs just fine. Air handler is in closet near family room, so cycling is VERY annoying. Replaced thermostat, but no difference. Does anyone have a suggestion?

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  • kirby90 Jun 03, 2009

    I mean the fan that circulates the air.

  • kirby90 Jun 04, 2009

    I wonder whether it's actually the relay. As I mentioned in the post, if I change the fan switch on the thermostat from Auto to On, the fan starts without any problem and stays on.

    Here's a little additional info: model number is TWV048B140A1. Unit was manufactured March 1992.

  • vikketer
    vikketer May 11, 2010

    When you say air handler do you mean the fan that circulates the air or the compressor in the condensing unit


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Depending on the age of your Trane unit. The fan relay has a time delay. This is a solid state board on the relay. Most of the time they stick on or off. Check for loose wires. But start with relay.

Posted on Jun 04, 2009

  • James Stopp
    James Stopp Jun 06, 2009

    Iworked for Trane for 15 years. OK In the thermast when it call for cool it brings the fan on thru the Tstat. You may have a bad fan switch in the tsta. . If yhis is an old mechanical Tstat. That is your problem. I have certain procedures I use to troubleshoot. Try a new tstat. Pick up one at Home Depot. If you want to call me. I can walk you thru problem. Ok James 251-269-1443. No problem


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