Craftsman 1 1/2 hp air compressor model 106.152680 builds air but when it shut off it feels like air leaking out of pressure switch someplace.

Cbillgreene:

Your compressor is leaking air somewhere between the compressor head and the tank. With the compressor running, feel carefully around the ends of the tube that leads from the compressor head to the air tank. You will probably feel some air leaking around one end or the other. If so... remove the tube and find out which packing has failed.

Sounds like the reed valves in the head failed. you need to replace the head (usually cheaper to get a new compressor)

The problem with compressors not building pressure is usually a bad pressure switch or bad regulator. Does the motor shut off at 20psi or does it continue running and not build pressure? If the motor continues to run with no increase in pressure, the you should go over the machine looking for air leaks from your regulator back all the way to the motor. Any air leak while the compressor is running can cause the pressure to "peak" way before the intended shutoff that it is regulated to.

Check for a leak between you compressor head (pump) and your tank. Your pump output may be good but as your tank pressure gets higher the leak will not allow the tank to build up.

sounds like the pressure switch is faulty. not uncommon on compressors anymore.

When a compressor reaches set pressure, there should be a release of air from discharge hose thru the unloader. This release of air unloads the compressor head pressure. The unloader is usually located within the pressure switch. Easy to check. Follow discharge hose from compressor head to tank. There should be a brass/steel checkvalve at the tank. The checkvalve allows air to enter tank, however not allow air to be released back into discharge hose. If this valve is leaking, air will be released from the unloader constantly. Follow 1/4" tubing from checkvalve to unloader and listen for leaks. Repair as needed. If air is not leaking from checkvalve then check unloader mechanism with-in pressure switch. Parts are available at www.toolpartsdirect.com Good luck

you have a valve problem in head /or leaking head gasket /or a bad leak in system
take off breather and see if it is pulling air it sould not be pushing back
one other thing would be the unloader at pressure switch or tank check valve

The compressor will not auto shut off until it reaches the preset pressure which is usually around 100-130 psi - your problem is leakage of air from the oil filler cap suggesting that you have a failed internal valve.

look at he check valve

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