Question about Craftsman 3 gal. Air Compressor, 1.5 hp, Horizontal k

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Cycling compressor I have a small "pancake" has recently started to cycle on and off. In other words...the compressor builds pressure, stops and starts for about one second intervals? My assumption is the pressure switch is defective? Any Ideas

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  • kdmaske Dec 12, 2008

    Thanks for your very quick response! I checked all fittings and even took off the tub from the tank to the pressure switch and checked to see if a piece of rust may have partially occluded the pressure switch. Ok here is the kicker...the compressor had been sitting all day and was obviously cold...when plugged in the compressor filled to 150 lbs and shut off. I pulled the quick release valve and partially released the pressure until the compressor kicked in to refill the tank. I got away with this twice and on the third attempt the compressor shut off at approx 80 lbs and started to cycle on and off for about a second or two. I detected a slight "hot" odor? This has been a very reliable machine for many years. Again...thanks for your prompt response


  • opie3535 Jan 01, 2009

    On my unit, there is a box where all of the wiring is configured (for 115 or 220v whichever you choose) and there is a spring with a slotted screw in the center, Is this my adjustment for the shutoff ?


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The pressure switch will shut off when the set pressure is obtained. Usually about 100 to 120 lbs. If the compressor stops at lower pressure than mentioned you may try to adjust the pressure by looking under the switch cover for adjustment screw/nut.(no more than a few turns) Increase pressure by increasing spring tension. Quick cycling is usually caused by air leaking from tubing, drain valve or check valve. After compressor shuts off unplug it from the outlet and spray soapy water on all fittings and drain valve. Repair leaks and test for quick cycling, however the compressor should reach 100-120 before shutting off. Some small compressors have a thermal reset but that usually takes a few minutes to reset. Pressure switch is defective if it shuts off before setting mentioned. Enjoy

Posted on Dec 11, 2008

  • John Trevino Dec 12, 2008

    The compressor should not exceed the pressure stated on machine. Example most compressors list 125# others list 150#, however for longevity you should adjust to 110 -120#. The motor will work less thus last longer run cooler. Other caused of heat are leaking head gasket, leaking intank check valve and long extension cord. A leaking head gasket causes the air to heat up and takes longer to fill. Leaking checkvalve will cause back pressure on the compressor loading the motor. Test checkvalve by removing tubing from checkvalve with air in tank and spray soapy water there should be no leak, even a small leak will make the motor work harder. Finally when the compressor reaches set pressure, the pressure switch will release the air in the tube with a very small valve (looks like tube stem). Every time that the compressor starts there should be no air in the tube because this causes extra load on motor. Enjoy


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