Compressor Motor Is Getting Really Hot?

What can I do when my air compressor motor is getting really hot?

There are a number of reasons why this may occur. A better understanding of how you are using your air compressor will help.

Is this a new condition? By that I mean is the motor getting really hot something that is new, or has it always been the case?

If it is a new condition, then that suggests that something on the air compressor, or in the use of the air compressor, has changed.

Under Powered Air Compressor Motors Get Really Hot!

If this is a new condition, have you just started using an extension cord? That could be the problem. A too-small extension cord can starve the motor of power. The compressor motor may still run, but it is laboring under the increased stress, and that’s generating heat.

Compressor Motor Gets Really Hot
Image of compressor motor.

By the same token, if you’ve moved the compressor and plugged it into a different socket, what is the amperage rating of the breaker / fuse that supplies that socket? A too small breaker could under power the compressor motor.

Also, how far from the main power panel is the socket? When considering the use of an extension cord to power an air compressor, not only does the length and gauge of the extension cord wire have to be considered, you must also add the distance from the panel to the socket when determining the overall power supply distance.

If you suspect that it’s the use of an extension cord that may be the issue, move the compressor closer to the socket and plug its power cord directly into the socket. Did that resolve the issue?

If you Google wire gauge for compressor motors you will find sources to provide a guide to what gauge, and breaker amperage, is required to properly run a compressor motor of a specific horsepower.

Or, consider using a longer air line rather than any extension cord. Your compressor motor will thank you, last longer, and the air tool will not be negatively impacted by supplying the air through a longer air line unless the air line doesn’t delivery enough air. Then a larger air line will be required.

Using The Air Compressor For Too Long A Period

Some folks don’t realize that most air compressors have a duty cycle. That means that they are designed to run for a period of time, and then be idle for at least the same length of time to allow components, including the motor, to cool down.

If you have been running your compressor for more than 10-15 minutes at a time with no rest, consider timing yourself, and shutting down using the compressor every 10-15 minutes for that same length of time to allow natural cooling.

Even smaller air compressors that have a 100% duty cycle, which implies that you can run them continuously, really cannot be run non-stop. Give every air compressor a break every 10-15 minutes. That will extend the life of all components on the compressor, including the motor.

What else might be happening when a compressor motor is getting really hot?

Heat Transfer From The Pump

For most reciprocating (piston type) air compressors, the compressed of air creates a lot of heat. This is why most air compressors have a warning sticker about the high temperatures the pump head and line to the tank may experience. This heat generation is normal, and as long as you are not exceeding the compressor duty cycle, isn’t a problem.

However, if your compressor pump is lubricated, and you haven’t checked to be sure that the oil sump is full to the correct level, that could generate a lot of extra heat… right before your pump fails!

Check the oil level if it is a lubricated compressor pump.

And, if you haven’t changed the oil in recent memory, know that old oil loses its ability to lubricate properly, and friction within the pump could be created excess heat.

Is It A Capacitor Issue?

Most air compressor motors will have a capacitor or two. Some will have a start capacitor, some will have a run capacitor, some will have both, and some air compressor motors will have a combined start/run capacitor. The capacitor aids in starting, and in some cases, the running of the air compressor motor. This page explains their use in detail.

If a capacitor is failing, the result can be an air compressor motor that gets really hot. Ultimately, this heat will cause the motor to go off on thermal cutout, to protect itself from heat damage, yet if the capacitor is not replaced, ultimately the compressor motor will be damaged.

If none of the other issues noted above are able to determine the cause of the too hot compressor motor, check the capacitors. See how to test your compressor motor capacitor near the middle of this page.

Still have a problem with your air compressor motor getting really hot? Post a question in the comment box below, and with any luck a person that has the same issue will provide help. Give as many details about your compressor as you can, will you? This will help others help you!

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2 years ago

I just purchased a used air compressor. tank was empty when I got to sellers, we turned it on and everything ran fine, I had him shut it off just before getting full. Once home I installed a dedicated line for the air compressor. So new breaker, outlet, plug, and pressure switch, changed the oil, cleaned the air filter and a new oil sight glass. Plug it in turn it on runs perfectly fine until 50-60PSI it trips the breaker ( not the motor thermal protector / reset button. Unless they can reset themselves). This happened about 3 times. After… Read more »

3 years ago

I have a All Power quiet zone APC 4406 that gets hot when the motors are not even running. Please help Me !!!

Ezzio Terroni
4 years ago

I have a delco 1.5hp 215t(odd one with 7/8 shaft) motor from 1946 on a Kellogg a320a and it is popping the breaker and getting really hot. It is a 110/220 that I have wired for 110 unfortunately. The motor was not designed with a run capacitor but I was wondering if installing one would be possible or helpful for my issue.

Frank Long
4 years ago


4 years ago

My 6 hp compressor motor runs for about 10 sec. then trips the breaker. In trying to get a reading on how many amps it was pulling I had to reset the breaker and try to start it a couple of times. After about 3 attempts I noticed the motor was getting very hot. I tested the capacitor which read 29.7 microfarads. It’s rated at 30 mfd +/- 6. Any ideas or suggestions? Thanks!