Tip & How-To about Air Tools & Compressors

Air Compressor Burn-Out

Small, easy to transport air compressors have become very popular over the last 25 years. However they do have their drawbacks.
The motors on these small compressors generate alot of heat as they cycle, especially under higher tank pressures (PSI's) and air volume usage (CFM's). They work very hard and run more frequently. In time, this heat creates increased resistance in the rotating armature windings (which act as quickly reversing magnets against magnets in the outer case of the motor for thrust to rotate). The magnetic force weakens, the motor gets weaker and hotter and has to work harder to do the same job.
When an air compressor motor seizes in it's cycle and hums or buzzes, it is over heating to a point where a thermostactic relay will break electrical contact (to prevent Fire) and the motor will have to cool before it will run again. each time this happens you are reducing the life of the motor by several hours.

To maximize the life of your compressor, use the following guidelines:

1.Always use the shortest possible cord and plug directly into a 20 amp cicuit when possible,no extension cords! SHORT WIRE+LONG AIRHOSE- electrical current is lost through longer wire and requires a larger gauge (diameter) to carry the current.

2.Make sure the plug contacts are clean- as with automobile batteries:CORROSION=RESISTANCE=HEAT=WEAR.

3. Should your compressor begin to stall during its cycle, attempt to turn it off or quickly or reduce the pressure in the air tank to reduce the load on the motor- while the motor is moving a fan blows air through it to cool it.

4.Should the motor overheat, let it cool untill you can touch it with your hand and bleed most of the air from the tank to minimize the start-up work load.

5.Remember to try to drain the tank after each use to minimize corrosion due to moisture and minimize load the next time you start it up.

Following these guidelines will increase the life of your compressor motor several months if not years.

-Remember-
BROKEN TOOLS CAN'T HELP YOU BUILD OR FIX ANYTHING

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1 Answer

I have a 30 gal 5.5 hp oil free Craftsman air compressor. It was brand new several years ago but never used it. It set in the original box in the garage. Went to use it today and when plugged in to start break in process it just hums. Got any ideas. Thanks PJ


Are you a mechanical type person? There is a fast and easy way to test the motor but it is not recommended for anyone who doesn't do this for a living. I have replaced 4 shaded pole motors in the last 3 years that did the same thing and never had a problem with a capacitor start or capacitor start/run motor. If the motor hums, it is trying to run. Try giving the stator help getting started while the motor is humming. Use a small piece of wood or soft plastic. Any non-conductor will do. Look inside the rear of the motor and you will see the field coils around the outside surface and the stator is the round thing in the middle of the motor that rotates. Use the non-conductor to start it turning in the direction it would normally run while the motor is humming. If the motor starts and runs ontill the pressure switch shuts it off, the motor is bad. If it has a capacitor on it, try replacing that first. Please let me know how this works out for you.

Apr 02, 2011 | Craftsman 33 gal Air Compressor 6 hp...

2 Answers

We have a Craftsman 15 gallon air compressor, model # 919.166442. It has worked fine for small jobs for the last few years. Went to turn it on and it simply won't turn on. It won't pressurize. Is this an easy fix- what do we do?


Hi, my name is John. Welcome to FixYa. Will it come on at all? Check the outlet circuit breaker, if it comes on at all, check where the line comes form the pump to the tank, there got to be a leak, you may have to remove it in order to check under it. Check for a reset button next to the wire coming to the switch. Thanks for choosing FixYa...John

Nov 24, 2010 | Craftsman 15 gal Air Compressor 3 hp UMC...

1 Answer

The motor is running. Belts and pulleys are turing. oil level is good. No leaking from tank or conectionslbs. Motor runs contiuously tank Air pressure will not rise above 25-50.


While the compressor is running and has reached point of not attaining higher pressure remove air filter and place your gloved finger over the intake hole (be carefull may be hot). If compressor is working properly you will feel suction, if however you feel air blowing out of intake most likely blown head gasket /s and or broken reed valves. Easy to fix however, look for parts at mastertoolparts.com

Nov 03, 2010 | Coleman 6.5hp - 80 Gallon Vertical ASME...

1 Answer

I have a 25 gal compressor and it will not build pressure. The motor runs but will not build pressure. The compressor is about 25 years old


You got a good life time with this. The compressor has seals or "rings" which wear out over time. Replace them and your compressor will love you. It won't hurt to check all the lubrication points. This procedure is easy for even a novice but may require a special tool. Go to your local small engine repair shop and ask. They will be glad to help you.

Aug 05, 2009 | Craftsman 3 gal. Air Compressor, 1.5 hp,...

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