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Sears Air Compressor Bogs Down – Troubleshooting Sears Air Compressor

Published Categorized as Air Compressor Runs Slow Bogs Down, Sears No Comments on Sears Air Compressor Bogs Down – Troubleshooting Sears Air Compressor

If your Sears air compressor is bogging down, and you can’t quite figure out why it can become very frustrating. Fortunately, this guide will provide you with the most common reasons why your Sears air compressor bogs down, along with existing reader questions and responses.

Table of Contents

Most Common Reasons Why Sears Air Compressor Bogs Down

Diagnosis of the problem may not always be so easy as there can be many things that can be the cause of the Sears compressor bogging down. However, here are some of the most common reasons why your Sears air compressor bogs down and runs slow:

  • Use of extension cord
  • Additional power-drawing appliances
  • Faulty unloader valve

Use of Extension Cord

If an extension cord or power bar is being used, you should remove it, and plug the air compressor power cord directly into the wall socket to see if that helps. This is because the extension cord or power bar will underpower the compressor.

Additional Power-Drawing Appliances

If you have too many other power-drawing appliances on the same circuit as the feed to the compressor you could be heavily underpowering the compressor.

Ideally, an air compressor should be powered from a socket that leads directly back to a 15 amp (minimum) or a 20 amp breaker or fuse at the panel. If other appliances are in the line that feeds the compressor, you should shut them all down before you test the compressor again.

Faulty Unloader Valve

The compressor unloader valve is likely failing. To check this, you should open the tank drain and let all of the air out of the tank. This process will emulate the unloader valve function, and at the same time, remove any water buildup inside the tank.

After doing so, close the drain and power up the compressor to test it. If the compressor starts easily and runs up to cut-out pressure, it is now time to service or replace the unloader valve.

For more detailed information on this topic, visit our Air Compressor Bogs Down – Solutions & Diagnosing Problems guide!

Reader Questions & Responses

Sears Portable Air Compressor Slows Down and Trips Off – Sears Air Compressor Troubleshooting


Sears portable air compressors 4hp single-phase 115V. This old sears air compressor runs till it gets about 15 psi. then slows down and trips off.


If it hit 15 PSI and tripped a breaker, it might be the pressure switch, Glenn, but let’s look beyond that.

Since the motor is slowing, I believe it is reacting to an increasing load.

That load could be the back pressure from the steadily filling tank and the increasing tank pressure against which the pump must drive.

It could be a bad check valve too, could be that the motor hasn’t got the poop left in it to pump air past 15 PSI backpressure.

Or it could be something in the pump itself.

Is the problem repeatable? Do you re-set (what is being reset, the air compressor thermal overload switch on the motor?) and exactly the same thing happens again?

Another consideration is whether the run capacitor is weakening or failing, assuming that you are not using an extension cord that is choking the power supply to the compressor.

Any chance you could upload a photo or two and more details about the compressor actions would help.

Keep us posted, if you would.

If you have any questions regarding a Sears air compressor bogging down, please leave a comment below, with a photo if applicable, so that someone can help you!

By Bill Wade

About Air Compressors has been helping folks with their Air Compressor Problems since 2002 online. We're a community of DIY and Compressed Air professionals who are keen to support everyone across the globe with their air compressor issues and troubleshooting. Whether you're trying to identify an old air compressor, or troubleshoot an error code on a sophisticated new industrial air compressor - the community at About-Air-Compressors.com is here to help you

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