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Lennox central air system keeps shutting down.

Last week i noticed the outdoor condenser for my Lennox AC was not running but my air handler still was. So I shut the ac off at the thermostat and checked my breaker panel. All seems good out there. My air filter didnt look too bad but I changed that anyways. The outdoor condenser is pretty darn clean inside and out from what I cant see. Also, drain pan for the air handler doesnt seem to be over flowing. Call placed to my local HVAC and have an appointment for next Monday.

For giggles, I turned the AC back on a few days later and the condenser turned on and was blowing cold air, but then shut off about a half hr or so later. Did same thing, and it turned on. But I immediately turned it off and it has been since.

Any idea what the issue would be? Its about 10 years old but in good shape. Dont really have the money to completely replace the system at this time.


  • mattmia2mattmia2 Member Posts: 1,312
    Is the cap good for the fan motor in the condenser (or the air handler/furnace for that matter), do you have some air flow but not enough because one of the motors isn't running at full speed because of a bad cap? Is the high pressure switch or overload for the compressor tripping out because of inadequate airflow so the high side pressure is going too high?
  • HVACNUTHVACNUT Member Posts: 3,363
    I say auto reset on low pressure or thermal overload on the compressor. Or a pitted contactor. Or a weak cap. Or a loose wire. Or intermittent Y contact in the thermostat.
    Can't wait till Monday night.
    What do I get if I win?
  • djc2232djc2232 Member Posts: 113
    A high five. At first i thought it would be electrical. But after a day or so when i tried it again it fired right up. I had it serviced last spring and all the pressures and readings the tech got were good. Or so he told me. Worked great all summer and this year as well no problems.

    Fan seems to be running full speed when it does. When it is running it doesnt seem to make any different noise. It still pushes air pretty well.

    Im hoping its not a gas leak anywhere and wouldnt think it would be. The system to me seems to be in pretty good shape with no signs of corrosion.
  • HVACNUTHVACNUT Member Posts: 3,363
    > @djc2232 said:
    > Also, drain pan for the air handler doesnt seem to be over flowing.

    Can you clarify?
    Is it a horizontal A/H with an Emergency pan underneath? Do you mean there's water in the pan but not enough to overflow? Is there a float switch or water sensor in the pan?
  • djc2232djc2232 Member Posts: 113
    It is horizontal. And I dont believe so. My drain got stopped up once and the pan over flowed and I had water all over the floor. Didnt take much to get it unclogged. Just some gunk. But wouldnt that stop the air handler as well?
  • mattmia2mattmia2 Member Posts: 1,312
    It is in the right era for them to have used thinner copper in the evaporator tubing and sometimes they leak now. Could be shutting down on low pressure because of a refrigerant leak. Or a bunch of other things.
  • djc2232djc2232 Member Posts: 113
    Wire from thermostat was loose an burnt out at the connection at the condenser. Wire was cut and reconnected. Should fix the issue. This weekend we have a warm up and will have the AC on.
  • unclejohnunclejohn Member Posts: 1,555
    I would replace the capacitor anyway. 10 years is long enough for todays caps.
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