How to set the pressure switch on your Harbor Freight air compressor

Instructions to properly adjust the air pressure on your air compressor purchased from Harbor Freight. This is my video demonstration for a visual understanding of what to do. Nearly all pressure switches are similar and this also works on water pumps for your house, irrigation pumps and some other applications on the farm. I learned how to do this when I was employed as a diesel mechanic on a large farm.
This demonstration was on a 21 gallon Central Pneumatic air compressor, other models (US General) sold by Harbor Freight will have a similar pressure switch.
Disclaimer:
Be aware that you are dealing with live electricity and the air tank is a large accumulator that can discharge air if you turn this up too much. * This video is for information only and you are responsible to work safely. We are not responsible for any incidental damages as a result of using this information.
Never exceed the specifications set by the manufacturer of your equipment, it may become unsafe resulting in personal injury and or damage to the equipment.

[@JDMGUYTA22]

This video is great, as I am getting serious with air compressors, this is very helpful tip for novice folks like my self who doesnt know much about compressor setting.

[@weightdr80]

This is just what I was looking for. I have a Devilbliss Pro 4000 compressor. I lost the manual so this video was very helpful. My tank has labels on it with the specifications. One label says it was tested at 150 PSI for a safety check. It is supposed to be able to go up to 120 PSI but the manufacturer set it a 90 PSI. That is not enough to operate a 16d nail gun. Thanks to your video, I can now carefully set my tank to 100+ PSI and try the nail gun again. Thanks for the tips.

[@proulxlaw]

Excellent! I have the same compressor and your demo was right on and a huge help. It helped me fix the problem that I was having and how to dial it in to wring more performance out of it. Thanks for sharing.

[@garyhgaryh]

Thanks for the info! Great video. I just picked up a 29 gallon 2HP 150max psi from HF (oil'ed). I love that compressor. I noticed it will pump up and stop right above 145psi. I wanted to increase the cutoff so it will be at 150psi. The next day I watched the gauge closely as it compressed the air to the cutoff and I noticed the cutoff was indeed at 150psi. When the pistons in the compressor stops, the pressure drops just a bit. If your cutoff is within 5psi of cutoff, I wouldn't adjust.

[@struebel232]

You are dead On Man! Thanks for the Great Information... And Saftey 1st always!!! No-one could have done this better! I have Had to do the same to Mine, Also Swaped For a Longer And Thicker Power Supply Line As My 8 gallon cord was Cut... But You Did a Wonderful Job On Everything! Always Like Said Take Baby Steps In Adjusting Pressures.

[@sambking]

Excellent! Just what I was looking for!

[@TOBORE8THMAN]

Thank you. I think you did a fine job with this review.

[@jburke1968]

I have 2-21 gallon HF air compressors and 2-15 gallon storage tanks I use for my shop. I had to set the pressure regulator on one of them to match the other one. know each will shut off at the same time. This is still cheaper than buying a bigger air compressor.

[@cliffordelsom]

Very informative thank you

[@jster1963]

THANK YOU SOOOO MUCH!!!! I have the exact same compressor and my pressure was exactly like yours. I was able to set the new pressure in about 1 minute thanks to your vid! Also, you reminded me to change my oil. I didn't realize I should have done a break in, but I sure will next time. Thanks again......jster

[@ncrdisabled]

thanks for the great video now I can adjust mine to T120 max and 85 cut in .

[@HangImHigh]

great job thanks!!

[@dollman0]

The pressure regulator was faulty and set far below the spec listed on the label. This is a common problem with Harbor Freight equipment. I bought this for the air tank and adding a 2nd pump increases the CFM. I set this up to 110 as labeled but my CH still is a far better air compressor and much quieter.

[@HWoodCreations]

Another great video dollman0! After reading many of the reviews on the HF site for this compressor, it sounds like quite a few of those guys would have benefitted from this video.

[@IMADABCI]

Excellent video, thanks! Is there any way to set the cut on pressure without affecting the cut off pressure?

[@dollman0]

@ncrdisabled You can also buy a new safety plug with a higher rating if it gives you any trouble. The valve on my pancake compressor is 130 PSI, the guidelines is 10% higher than your air pressure or 15 PSI, whichever is greater. One of the reviews on a portable air tank said the blow-off valve gave them some problems and it was removed, NEVER REMOVE the SAFETY VALVE but get a higher pressure if neccasary.

[@dollman0]

@stymye You have two choices, return the compressor several times until you get a compressor that is properly set, or set the pressure to the level specified by the manufacturer.

[@knowsbetter1]

great demo. I have a sears compressor that does not stay running enough to get 40-50 Lbs and once it starts draining it will not come back on. I have to turn switch off for about 10-15 minutes and flip switch on and it will run to about 40-50 Lbs. the compressor is a re manufacture, and not that old. Is it part of the pressure switch and can I tweak it like yours?

[@voweeks]

i have the 67847 unit. i got it part of a close out this winter. some times when i go to start it up while it already has pressure in the take it bogs done and trips the braker withing 5 seconds. if i drain out all the ari and flip the toggle switch a few times it will "warm up" and run great. any idea what is causinbg this. i havent changed the oil yet. i will get some 5w30 for it.

[@bagofnailsbon]

Thanks for this video. I have the same exact model and just used your instructions. Yesterday I was trying to free a lower strut bolt on the back of my cr-v. I looked at the compressor after it finished cycling and both the tank and the tool were at 90! Now, the tank is around 115. I'm playing with the tool pressure, but I'm trying not to be dumb and hurt my tools. Is anything above 90 bad for tools? (impact wrenches, cut-off wheels, etc.) Or can they handle 100 or higher? Thanks again!

[@dollman0]

@hendu3270 I tried to show you exactly how to do it safely and go in small steps until you get the desired pressure. If this pressure switch gives you any trouble, replace it with a better quality switch, it is somewhat universal. Remember, the safety valve is rated at 125 PSI and you can buy a new one in any PSI rating (10% higher than max PSI)... Its cheap manufacturing, you can expect some defects. Once I set the pressure up, it works a lot better.

[@MrSwascott1981]

Hey I've got the 67847 the black 21 gallon I'm having a hard time with the crankcase gasket it keeps leaking oil and it won't kick back on as you use it. Any suggestions

[@shawndels8463]

Help my pressure switch cots off after about 2 r 3 seconds what next ..Great video 125psi harber frieght

[@TheJrogersp]

I have a 21 Gal. 125 psi 2.5 hp H.F. Compressor. When I turn it on it will pump for maybe 1 min. or less and shut off and I cannot get it up past 40 lbs. Will this adjustment make it right? or is there another problem.. This is the 2nd. one I have gotten from them. They will not take this one back since I already had them replace the first one. I really hate their return policy even if you buy the warranty. Thanks!

[@stymye]

did you tell people that this will void the warranty...?it says so in the instruction book

[@dollman0]

@voweeks If you use 5w30 oil, make sure it is mobil-1 or a quality synthetic.

[@dollman0]

Its simple, you have an inflation pump not a true air compressor. The pump is equivalent to a model car engine and there is no way to make it pump faster. My 5 HP (Peak) compressor is rated at 2 HP continuous based upon the electrical HP rating defined by 741 watts... I would suggest you buy a bigger compressor if you plan to run air tools or have a heavy air demand.

[@gandl2123]

I have a Model 90234 4hp 10 gal Harbor Freight compressor and there is a spring in the pressure switch that holds the button in the up (on) position. When you pull the red button up the compressor is on, and when you push the button down the compressor is supposed to go of....the spring that is supposed to hold the button up is missing and someone has fashioned a home-made spring in there and it does not work. Can I get a spring for a pressure switch? Does anyone know how to get one? Tks

[@dollman0]

Contact customer service and explain to them that the compressor will not function as it is intended. Remind them of the Magnason Moss Act which requires them to honor the published warranty. If Harbor Freight still will not repair or replace your item, contact consumer protection in your state (office of attorney general). Harbor Freight is required to provide you with a functional compressor (Unfair & Deceptive Trade Practices Act) regardless of what their store policy is.

[@dollman0]

@MrNjl007 I have one of these pancake compressors and I will see what I can do about making a video... You may consider replacing the pressure switch with a better quality unit since most HF compressors seem to have a problem with the check valve and the pressure switch.

[@SDsailor7]

dollman0 did you say that you backed out the pressure adjusting screw or did you screw it in to raise the pressure? thank you best wishes

[@willc5512]

I will add that the inner diameter of the brass fittings they supply are garbage. They look well made but they leave too much meat in the middle. Dont believe me take your fittings off & go to a hardware store & compare the inner diameter. Hollow fittings from the store give more airflow to the tool. So better fittings that dont leak takes away the need to adjust the cutout pressure.

[@evilthoughts77]

This video makes no sense, when you buy a compressor it is set to manufactures specs. If you need more air buy a bigger compressor why tamper with one that just makes no sense..as far as using air tools each come with a stamped label for max psi/bar on spay guns sanders impact guns and grinder and most have built in air adjust ments or simply buy a air regulator to tell what psi is at tool.