Compressor shuts off before reaching pressure

by jon dee

compressor shuts off without reaching full operating pressure (circuit breaker trips)



Make sure the power supply to your Harbor Freight air compressor is "clean". By that, I mean no extension cord being used, and no other appliances pulling power from the same circuit the air compressor is on.

If the problem persists when you have clean power, then it might be a failing pressure switch allowing a short and popping the breaker, it could be the motor is laboring and pulling too many amps, it could be the start/run capacitor isn't working right... many things.

What pressure does it reach before the breaker pops, and is the breaker popping at the same pressure on the compressor every time?

Post a response here please, if you wish, so I can follow the thread.



Comments for Compressor shuts off before reaching pressure

Click here to add your own comments

Jan 23, 2017
Remove rubber o ring
by: Forrest

Mine would trip almost every start. I took the brass valve off top with 14mm and took the red rubber o ring out and has never faulted again. 3 months later

Dec 07, 2016
compressor always needs resetting
by: harry

hi what up. i have my compressor for about 2 yrs.the same one you have.from day one i have to hit the reset 10-16 times before it will stay running.frist i used an exstion cord so i did away with it dircit into outlet.still dose it and i have tryed differant outlets with same resutls.and i do not use that much

it is so loud it hurts your it is full of air 150 psi.shuts off and go to check the air in my tire and i put in 5lbs.and the compressor kick back on and it keeps doing that so anything i am working on on and off on and off.

Mar 29, 2016
Harbor Freight 21 Gal 2.5 HP # 61454
by: JR

Same problem, if the pressure is somewhere between 90-40 PSI (Even a little less) the motor bogs down and trips the reset button, I can tell the motor is laboring trying to turn over even when it hasn't been in use or hot, the thermal (Reset button) pops, I have to completely drain the tank, then, the motor will run up to 125 PSI to fill the tank.

It's not my garage or outlet power, been running a 5.5 HP 26 Gal on that same outlet for years, there's something wrong with this compressor, especially reading all these other same sounding problems. Lucky for me I just bought it and hasn't been 30 days yet. It's going back to HF to get my money back, after reading these other complaints and having the same, not going to chance getting stuck with one.

Aug 07, 2014
Regarding Brand new and won't run.
by: Bill

Odd that the regulator gauge reaches 85 PSI but the tank gauge doesn't read anything.

I would expect the reverse if the regulator was turned down to zero.

It were me, this one would be going back in the box and on the way to the store for a new one.

Anyone else?


Aug 07, 2014
Brand new and won't run.
by: Kelly Dillon

Just put together this brand new compressor yesterday. Followed break in procedure no problem. Then drained the oil and refilled (to proper level) with compressor oil supplied by Harbor Freight.

Restarted compressor and it ran until regulator gauge reached 85psi.

The tank gauge never moved from 0 psi.

At this point it sputtered and quit. I tried to restart but it wouldn't. I figured it overheated so I waited 30 minutes and tried to start. It wouldn't start with the switch. When I hit the reset it sputtered for about 2 seconds and kicked out.

I let it set overnight and it did the same thing this morning.

The replacement oil from Harbor freight seemed to be a little thicker than what came in the box with the compressor. Is this the issue or is it something else???? Please help

May 16, 2013
reset switch
by: Anonymous

OMG fellas. don't make a huge project out of this. by-pass the reset switch. Tha'ts all that's wrong. Just cut the wires,twist them together and spin a yellow wire nut on there.
That's one line of thought. On the other hand, if the reset is tripping due to overheating of the motor, then by following your advice you will, for sure, overheat the motor. Not good if you want your motor to last.


Aug 21, 2012
Reset trips right away
by: Luis

My 21-Gal compressor trips the reset button right away and no matter how many times I reset it, it does the same thing over and over. The motor doesn't even get a chance to build any pressure up. First out of the box, it worked fine and I used it one time for about two hours with no problems. Now it doesn't even want to get going. Any ideas? Thanks.
A couple of things to consider. First off, are you plugging it directly into a wall socket or using an extension cord. If using a cord, either get a heavier duty one or don't use it. The other is, you mention that it goes off before it builds pressure, yet is there pressure in the tank? Before you try to start it again, open the tank valve and make sure the tank is empty. Close the drain and start it. Did that make any difference?


Jul 22, 2011
pressure switch removal and replace
by: Anonymous

pressure switch is central pneumatic for 2.5hp 21 gallon compressor.


I wonder if yours is the condor switch?

If so, you should be able to get details here:

Jul 19, 2011
pressure switch removal
by: Anonymous

how do i remove switch and replace it with a new one.there are 4 screws on the bottom and a red button on the top. how do i remove the red button on top?
thanks, jd


What make of switch?

May 18, 2011
by: jon dee

pressing the reset button after the circuit breaker trips allows the compressor to reach full runs about one minute before it cuts off each time


Hoping that you have clean power, as noted, at what pressure does the breaker trip? Same pressure each time? If it's happening a differing pressure points, then it may not the pressure switch.


Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Harbor Freight Compressor Issues.

internal pressure regulator

by Jack Schauf
(Collvile wa 99114)

The internal on my new model 67847 21 gal compressor. shuts off at 40 lbs. I want to know if therev\ is an adjustment capability that is owner friendly. I live a good distance from any outlet and need my compressor. The one time i tried it was to air up a truck tire had to keep waiting for build-up. the line pressure regulator sets to 90 lbs.

Bill says....

Hello Jack. I'm not sure what you mean by "The internal" on your air compressor?

The device that turns your compressor on at low pressure, and shuts it off at the high pressure, is the pressure switch.

Have a look at the PRESSURE SWITCH page and see if what it says is what you are looking for, OK?

Add a comment if that's not what you mean.



Comments for internal pressure regulator

Click here to add your own comments

Jan 30, 2017
10G cuts off seconds after hit start
by: Rhyder

My compressor would trip the reset switch after a second of throwing the on switch, motor never cut on, sounds like a pump hitting 2 or three times then trips

saw someone mention covering the air I do, put my palm over the air filter holes, flip the switch and presto the motor kicks in and it fills the tank, no problem..I removed my hand from the filter after about a second after the motor kicked in and it kept going...

looks to me that the air filter design is defective or they have a bunch of defective air filters going out that either fail right away or after only a few uses.....

Dec 26, 2016
Not the fix but...
by: Anonymous

We bought the same poorly designed compressor from HF. Our compressor has the same problem of not being able to automatically restart after some air usage right out of the box.
If you cover the three inlet holes on the air filter, the compressor will start right up without laboring, and run until the pressure switch shuts it off at about 125psi. I believe the real problem is too weak of a motor, as the compressor section pumps up briskly.

Try covering the air filter inlet for a few seconds to allow the motor to come up to speed, as this works with our compressor.

Mar 13, 2014
Same problem with my 21 gal Harbor Frt compressor
by: Anonymous55

I'm having the same problem. Goes down to 90 lbs, tries to restart and sputters blows the breaker on the motor repeatedly. This thing is BRAND NEW!, so it must be a design flaw. Maybe I can get them to send me an unloader valve.
Does your unloader valve work? See the pages about why air compressors won't restart and pop breakers. It could be a power supply issue, or other related issues as well.


Jul 02, 2013
Won't restart at 90 psi
by: Tom

I have a similar problem with my HF 2.5 HP, 21 gal vertical AC. Starts and builds to 125 psi just fine, but when the pressure drops below 90 psi, when it is supposed to restart on its own and refill to 125 psi, the motor tries to start but sputters out and trips the breaker. I keep resetting the breaker and the mtor keeps retrying but alweays sputters then trips the breaker again. I have to drain the tank completely before the motor will resstart, at which point it fills the tank to 125 psi in good order. This unit replaces one I just returned under extended warranty with exactly the same problem. What is wrong with the design? 2 in a row with the same problem? C'mon! Thanks for any ideas.
The symptoms point to a failed unloader valve. Empty the tank, start the compressor, and monitor the unloader valve to be sure that it works when the compressor reaches cut out and stops.


Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Harbor Freight Compressor Issues.

the compressor takes along time to pump up pressure and won't top off

by Don Gallipeau
(Deridder, La. USA)

The top off pressure is 120 lbs, but the compressure only builds up to 100 lbs and won't go any higher, (and this takes over a half an hour) I figure the compressor is wore out, the motor is good. is there any way I can buy a compressor or get the parts to rebuilds the one I have.????
Thank you for your time & consideration.
Don, it would be worth your time to look at the troubleshooting pages on the sitemap page, and read the one about why air compressors run but don't build pressure.

There are a number of reasons why an air compressor runs but doesn't build pressure, and they are common to many of the Harbor Freight air compressors too.

You don't provide the model, so I cannot comment on parts, though if you do a browser search for your compressor model number, I suspect you'll find a number of sources.


Comments for the compressor takes along time to pump up pressure and won't top off

Click here to add your own comments

Apr 24, 2016
Won't shut off
by: Anonymous

I have 21 gallon 2.5hp pneumatic air compressor. It won't shut off at 125psi it goes to 150psi then the pops and releases air. Is it the pressure switch? It's only been used for a year

(Please start a new thread - Moderator)

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Harbor Freight Compressor Issues.


by Larry
(Medford, OR)

Will only go to 80# then shuts down. Borderline pressure for my nail gun. I contacted HF parts. They told me the pressure switch which appears solid state can't be ordered.

Do you know where I can get the pressure switch?
Since I don't know the model of your Harbor Freight air compressor, I cannot advise you, Larry.

With a model number I (or you for that matter) can do a search for parts.

Depending on the style of pressure switch, there are quite likely a number of outlets that offer a non-OEM switch that will work just fine.

And yes, typically, if your air compressor is shutting down before the cut out pressure is reached, then it is likely the pressure switch at fault.



Click here to add your own comments

Jan 30, 2014
pressure switch
by: Doug in

Just so you do not make a common mistake:

Measure the diameter of the threaded part -

Most likely:

If it is just under 1/2 inch, that is 1/4 inch pipe size.

Just under 3/8 would be 1/8 inch pipe size.

You can compare the size and the fit at a local place that carries pipe.

Also, it could be metric, or British, if the regular pipe sizes don't fit well.

Good luck and have fun.
Or, you could see the NPT fittings size in inches here on the fittings pages of

And thanks again for the input, Doug.


Jan 29, 2014
Pressure switch
by: Larry

I opened the case and found a solid state device connected to the air resevoir with two wires coming out of it. This thing was about the size of a dime, or penny in diameter, and about 1" tall.

Jan 29, 2014
No model # on it...
by: Larry

Item 69486, doesn't say anything else on it.

Looks just like 95275 on their website.
Odd are good, then, that it will have the same style switch.

If you download the manual you will find a parts list and a drawing. #14 is the pressure switch on the 95275. Can you find this same part on your compressor?


Jan 29, 2014
ss pressure switch
by: Doug in

If you can get the switch open, you may find it is adjustable,..

If not, then what Bill said.

Click here to add your own comments

Add your own question or comment. It's easy to do. How? Simply click here to return to Harbor Freight Compressor Issues.