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

Table of Contents

Most Common Reasons Why Speedaire 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 Speedaire compressor bogging down. However, here are some of the most common reasons why your Speedaire air compressor bogs down and runs slow:

  • Too many other power-drawing appliances on the same circuit as the feed to 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 testing the compressor again.
  • The use of a too-small extension cord or power bar to power the compressor – 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.
  • The compressor unloader valve has failed – open the tank drain and let all of the air out of the tank to test this. This will emulate the unloader valve function, and at the same time, remove any water buildup inside the tank. Close the drain and power up the compressor to test. 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

Speedaire Air Compressor Bogs Down – Speedaire Air Compressor Troubleshooting

Question

I have a Speedaire air compressor 3Z323 That I bought from Grainger about 35 yrs ago. Great service through the years.

Yesterday, after removing the DAYTON capacitor a/c motor and the cast iron pump (in units with no disassembly) for repairing a pinhole in the side of the tank, I re-installed the motor and pump.

The compressor started working fine for about 35 seconds and pressure was indicating 40psi when the pump started slowing down sounding stressed and tight and the motor (DAYTON Capacitor A/C Compressor, V 115/230, A 17.8/8.9) made some screeching dry noise in the area of the axle (point of belt turning) although the belt tension was proper. I turned the power OFF immediately.

After removing the belt, I could spin the motor freely by hand. With the belt OFF, I turned the power ON and the motor was spinning on high reps without any noise. Turning the power OFF again the motor spinning slowly went down and came to a stop without any stress or noise. Oil was changed about 2 weeks ago and the level is to the top. I appreciate your input. Thanks. George

Response

Hi George…

I hope you are really good with a welder. It is not normally a good idea to try and repair a leaking compressor tank. The pinhole indicates that there is internal rust damage to the tank wall, and you may have the potential for a catastrophic failure along the way.

I would replace the tank myself as welding one spot will not fix other weak areas, and the welding process may damage an already weak wall further.

The absence of a photo of the compressor makes it hard for anyone to provide specific help as to the motor bogging down now when it did not before.

If nothing else on the compressor or the power supply has changed, I suspect that the check valve from the pump head into the tank has been compromised. That possibly happened when you were moving the tank around to fix it, and lots of tank crud got into the check valve and maybe prevents it from opening properly.

That’s my first guess, George. Maybe check that out and then post if that was the problem or not as a comment here?

Questioner

Hi Bill,

Thank you for your suggestion regarding possible air pressure valve failure causing the compressor bogs down. I was suspecting that but I had taken no action to explore it. After your suggestion, I will definitely check it out and post the result. Also, I will look for another tank. Thanks

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