DeWalt Air Compressor Won’t Start

Published Categorized as Dewalt 26 Comments on DeWalt Air Compressor Won’t Start

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There have been many folks that wish to inquire about why their DeWalt air compressor not turning on and other questions along those same lines. This article will present some of the reasons this may be happening and DeWalt air compressor troubleshooting suggestions made to resolve those issues, along with existing reader questions and responses.

Table of Contents

Reasons Why Your DeWalt Air Compressor Won’t Start

The main reasons as to why your DeWalt air compressor hums but won’t start are likely to be due to any of the following reasons:

  • Power issue
  • Fuse or breaker blows
  • Faulty pressure switch
  • Faulty thermal overload switch
  • Faulty unloader valve
  • Insufficient oil

Your first check is to make sure the DeWalt compressor electrical power plug in the wall socket? You should also aim to avoid using power bars and power strips because they don’t support the direct connection of machines to electricity sources.

If the compressor is creating an electrical fault then it’ll likely pop the breaker or the fuse will blow when the compressor attempts to start again. Circuit breakers will trip off when a power surge blows their fuses. These circuit breakers generally offer protection for power panels and equipment. If the fuses are faulty, you will need fuse replacements before being able to start your air compressor.

Check the pressure switch of the DeWalt air compressor if it will not start. Unplug the DeWalt compressor from the electrical outlet before opening the drain valve releasing the air from the tank down to zero and then closing the drain.

Are you hearing a humming sound, or is any noise coming from the compressor motor? If not, double-check for a thermal overload button or a reset button on or around the motor. Another thing to check is if the unloader valve does not operate as that may be why your compressor will not start the next time the pressure switch sends power to the compressor motor.

Oil-lubricated air compressors need a constant supply of oil to be able to run efficiently. When the pump’s oil level is below the manufacturer’s specification, your air compressor might well be in danger. You should check the oil level, and inspect under the pump area for any potential leaks.

Please visit our Air Compressor Won’t Start – Ways to Fix Air Compressor Won’t Turn On Problems guide for more detailed DeWalt air compressor troubleshooting & fixes!

FAQs (Frequently Asked Questions)

Why did my Dewalt air compressor stop working?

If your DeWalt air compressor stops working, inspect the power supply unit before running checks for things such as an air leak, an oil leak or a broken part. In some cases, you might have insufficient pressurization or airflow. In other cases, the compressor might fail to start up or stop running as prompted.

What would cause an air compressor to not turn on?

There are a number of reasons why your air compressor may not turn on, these include power issues, fuse or breaker blows, faulty pressure switch, faulty thermal overload switch, faulty unloader valve, or insufficient oil.

Reader Questions & Responses

DeWalt Upright Electric Compressor Will Not Turn On


I have a 1.5-year-old stand-up Dewalt compressor that will not turn on. It worked two weeks ago, and now nothing happens. You move the switch from Off to Auto and get nothing. No noise, no nothing. The tank is empty, not full so that is not the problem. It is plugged into a good outlet, that is not the problem. It is oil-less, that is not the problem. Any ideas? I spent $250 on a compressor for home use, I would expect it to last me many, many years. Thank you, by JC from Lakewood, CO.


JC, I suggest you obtain a multi-meter and use it to check and see if power is flowing through the on/off switch when you turn it on.

If power is getting through the switch to the motor circuit, trace the motor circuit (possibly remove the end cap on the motor to see the wiring) and make sure power is getting into the wires and reaching the motor itself.

That being OK, the start capacitor is suspect. There’s a page on this site linked from the troubleshooting page as to how to do that. See that page for how, if you are not sure.

DeWalt Air Compressor Doesn’t Want to Start


DeWalt air compressor doesn’t want to turn on, this is from Justin of El Paso.

DeWalt air compressor


Whoa. Tough one to answer Justin, since you don’t provide me with a whole lot of info, so it’s hard to figure out why your DeWalt compressor won’t start. Knowing the make and model would sure help.

Please visit the air compressor troubleshooting page here to find out why air compressors won’t start. There is a bunch of info there about things you can check on your DeWalt compressor.

After checking that out, if you are still having problems with your DeWalt air compressor please add a comment below.

DeWalt Oil-Less D55140 Won’t Start


The power supply is good, the tank is empty, no humming, no thermal reset button visible, nothing happens. Just stopped working one day, this was added by Gabriel of Richmond.


Gabriel, you say power is good. Can you provide a bit more info on that? For example, did you use a multi-meter to check where power is flowing to?

With the compressor tank empty, power should flow from the socket, to and through and ON/OFF switch, to and through the pressure switch, to the motor circuit. At the motor power should be flowing from the supply side of the motor circuit right to the motor. Is it?

If power is getting that far, test your capacitor to see if it’s shorted out. See that page on this site.

More information on DeWalt Compressors

For a broad range of information about DeWalt air compressors see the DeWalt air compressor brand page here.

If you have any questions regarding a DeWalt air compressor not starting, please leave a comment below, with a photo if applicable, so that someone can help you!

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I had this same issue, these compressors are very poor quality. I had to replace the switch module and it operated as normal again. I’m now having other issues though with the too much air pressure and the pump not shutting off before the safety valve releases the excess pressure. Dewalt is impossible to get ahold of – two hours on hold then cut off, online chat won’t connect, the email input erases your info

Could be time to change the pressure switch. Depending on model, they’re not terribly expensive.

Last edited 2 years ago by Doug in

Thanks, your exactly right, just figured it out yesterday and have one in the mail. Thanks!

You’re quite welcome. Happy to help.

I have a Dewalt D155141 compressor that for a while wouldn’t start very quickly when air was called for. Now it won’t start at all. I took it apart and did a continuity test for all the wiring and found that the break in continuity is at what I think is the capacitor (or is it a fuse?). There is no continuity between the two ends of the unit. It is the grey tube in the center of the picture. Can anyone verify if is is a capacitor or a fuse? Either way, can that be replaced?

Either a fuse or a thermal cut off. Any markings on it?
But I’m gonna guess the root of your problem is the brushes are shot.

Doug, what makes you say that my brushes are shot? I was able to get the motor working by directly powering the wire you see in the lower left of the pic.

Probably all those zap marks you made directly powering it. And the slow start complaint – that’s sometimes sick brushes. But if it’s not brushes that’s a good thing because apparently you can’t get them.

BTW, brush type motors don’t use capacitors.

So, are there any markings on the thing in question, or not?

On one end it says “250V” and on the other it says “10AMP BUSS ABC”.

It’s a fuse then. Your local big box or auto parts store may have them, or can almost certainly get them for you. Use your fave search engine.

You’re looking for “10AMP BUSS ABC with axial leads”

You may find a “Littlefuse” or other make. Doesn’t matter as long as it’s 10Amp, the case is ceramic and has the leads.

Last edited 2 years ago by Doug in

Thanks so much Doug! So would I cut out the old one then solder the new one onto the existing wires that are left?


Know that there is a fair chance the new one will blow too, unless/until the underlying problem is fixed.

” wouldn’t start very quickly when air was called for.” suggests there may be a bind or maybe you were using an extension cord?

You’ll probably need to buy a 5-pack, so you’ll have spare fuses.

Thanks. I don’t think I’ve ever used it without an extension cord in the 15 years I’ve had it.

Well, that puts me back to wondering about the brushes, armature, and windings. What gauge and length is the cord(s?).

Would it be possible or advisable to wire in a fuse holder?

Possible, or you could even use a circuit breaker, space allowing.

But if it’s that bad, I’d again suspect an underlying problem, which could be related to long-term extension cord use, or just wearing out. Possibly extending to the fuse wearing out (yes, they do).

If it works as it used to with a new fuse, maybe there’s nothing more to worry about.

Last edited 2 years ago by Doug in

I think that’s what I’ll do. I have been tempted to toss the whole thing in the trash but I really like it for what I use it for. Thanks again for all your help Doug.

What? Breaker?

I meant I will install an inline fuse holder and see what happens. Seems easier than soldering a fuse with axial leads in, especially as I have not been able to find any.

Oh, sure; that’s a viable work-around.

If it doesn’t do anything. Take it apart and there is a fuse inside of it. I switched out the fuse and it works again.

Thanks for that, Dale.

How do I get to it?

Sorry Trisha, I don’t get it. How do you get to what, please?

I have a DeWalt D55151 air compressor. When I switch it on it tries to start, slowly, but then trips the reset. I usually have to wait a minute or two before I’m able to successfully press the reset and get it to try to start again. It seems to have the correct amount of oil in it, but I don’t know if it was ever run dry or not. It’s just so sluggish when it tries to start. I want to think I should test the reset switch but don’t know how.

Any thoughts for me?

Yes. Same as the reply to Gabriel, directly above this post. Straight to the last reply line.