A/C Question - severe short cycling?

I have a Lennox A/C, and the compressor short cycles 3.3m on, 1.6m off, 67 times from 2PM to 8PM. And this was a mild day, 9 CDD. The wear on moving parts and wasted energy makes me cry. What is a possible solution? Also short cycles most of the day except morning.


It was recently serviced. I was given a new thermostat because the anticipator was too hot and the A/C always shot past the setting. Needed refrigerant. Certainly not fixed. We have hot water radiator heat so the A/C was put in within the walls. The compressor is outside and the cold refrigerant flow up to the attic to a "distributor" that sends cold air through the house. I am concerned about the short cycle wear on parts (solenoids, compressor motor,etc.) and the cold refrigerant stuck between floors during the short off cycle.

Update 2:


4 Answers

  • 1 decade ago
    Favorite Answer

    That's short cycling but not severe short cycling.

    The first thing to check is whether the thermostat is driving it crazy. My guess is not, but when you assume.... Anyway, turn the thermostat down all the way end ensure the short cycling continues.

    With that out of the way start looking at air flow through the evaporator. If the filter and blower are doing okay, check the condenser. Verify the fan is actually blowing air and wash the condenser out with water spray. If it is still short cycling it is time for a pro - the charge is probably low.

  • Anonymous
    5 years ago

    Sounds like you have a leak and your loosing your freon. Your low on freon again. AC units have pressure switches to protect the compressor from damage from damage by running without proper amount of freon. The AC is running during the day because the daytime heat is expanding the freon gas increasing pressure enough to keep the pressure switch from turning the unit off. At night the temp drops and the gas is no longer at the pressure it had during the day time heat there for the pressure which kills the unit to protect the compressor. Have the AC guy come back out and refill the unit and to check the entire unit for a leak. Once the leak is fixed this will remedy the issue. Hope this helps! My bad I just re-read the post. I read it wrong first time. Its running at night and not during the day.. However seeing that it was 3lbs low when he came out the first time it stands to reason it could be low again. Have him come out and recheck the system. 90% of the time you have a system short cycling its a freon level problem. If its low again hes going to need to track the leak and fix it otherwise you might as well purchase stock in a brand of freon so you get some of your money back. lol.. Its also a new build and a new system. Electricians and plumbers and all construction workers have a bad habit of hitting AC lines with nails when hanging siding, or tacking wires.... Hopefully thats NOT the issue seeing that it will take going into a wall to rerun new lines.. Either way its gotta be fixed. Sure your AC guy has seen this all the time! Happens in my area all the time! Still hope this helps!

  • 5 years ago

    That was several years ago. The off/on timing in this system is that the thermostat is about 5min and icing on the condenser is that 1 and a half minutes. After 4 repair guys came in, the last one had a light bulb go off for the 1.5 min off/on - icing on the condenser. He moved the freezing sensor an inch or two further away from the ice line, bingo, fixed it. It still comes back after the peak of temperature but not as aggressive. Said that when a new A/C will be needed, not soon, a better match will be installed.

  • 1 decade ago

    could be a few things: a refrigerant leak, and overchaged system, the wrong kind of refrigerant, dirty coils, iced coils/fan not working properly, bent fins, or an oversized system. If its a newly occuring problem its the first few reasons, if its a long termproblem its the later. You might be able to troubleshoot it yourself, but if your not sure about the fixing part call a tech. My dad spent years fixing problems exacerbated by owners trying to fix it themselves :)

    Source(s): daughter of an HVAC tech and teacher :)
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