Harbor Freight Air Compressor Pressure Switch Replacement (Again...)

We're back again with my 21 gallon Harbor Freight air compressor to once again attempt to repair it. Looks like yet another pressure switch failed and needs to be replaced. Good times!
Video Links:
Cheap Upgrades For Cheap Air Compressors ► • Cheap Upgrades for Che...
Air Compressors/Air Tools Playlist ► • Old Harbor Freight Air...
Stuff Links (these are affiliated):
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Teflon Tape ► amzn.to/3L8wiEg
Pressure Switch ► amzn.to/3k5npzm
Z Shaped Screw Driver ► amzn.to/3MneV2K
Want to contact me? [e-mail]

[@arthurgoldberg1963]

Thank you for your helpful video. I just changed the pressure switch on a different Central Pneumatics (Harbor Freight) Air compressor. It was a different model (item 95498, 2 HP, $ Gallon), but your video was still quite helpful. The pointer to the Oately pipe dope was also helpful. These pressure switches also must fail just by age and the rubber degrading. I went to use my compressor after it had been sitting for at least a year. It worked fine when put away, but just leaked air when I went to use it. It now works again after replacing this switch and with the help from your video. This switch also serves as a manifold, and at least on my compressor it seems the switch was put in and everything else added around it. I had to completely disassemble the compressor and reassemble with the new switch. A rubber diaphragm just seems like s poor design. I spring loaded piston would likely work forever without failure.

[@TheBrokenLife]

You're very welcome! Frustratingly, the rubber diaphragm design has been around forever and was quite robust in years gone by. I have a compressor in the family that is from the 1950s and I'd be surprised if it doesn't still have its original switch. We're dealing with the diminishing quality of modern manufacturing... but, we're also getting it really, really cheap. So...

[@whitetiger8652]

Excellent video! Thanks I have the same problem with the identical air compressor.

[@TheBrokenLife]

Thanks! I'm glad you found it helpful. 👍

[@C-M-E]

Not that HF are exactly known for quality parts, but if you're continuously knocking out pressure switches, there's usually something downstream that's pushing your pressure switch beyond its service values. While you've got everything torn apart, it's worth going through your check valve to make sure there's no debris from either tank rust (in older tanks with owners who don't drain regularly; can't say that's you, don't know ya); dirty air filters are also notorious for jamming up check valves. If you're using an oil-lubed compressor, there's also a better than average chance you'll find oil vapor/blow-by on it as the check valve is the primary contact surface when it leaves the tank and gums up check valve moving parts. Those three are very common for most any compressor regardless of brand, though some have looser tolerances or better spring pressure and take longer to stymie the components towards failure.

[@TheBrokenLife]

I'm guilty as charged on several counts there. 😆As this compressor stands now, it has eaten at least one additional pressure switch and that was pretty clearly caused by debris from tank rust getting into the bladder and causing it to tear. I have since replaced the entire machine. But... Across this compressor and others like it, I've probably replaced 8 of these switches that had no clear cause of death (some failed electronically, some leaked) and at least a couple of the replacements were defective out of the box. The simple truth is that these switches are extremely poor quality. But... You get what you pay for too. These switches are usually around 10 bucks. I had previously considered servicing the check valve (and have a replacement), but the odds of irreparably damaging the tank trying it were too high to bother at the time. Now that it's retired, and eating head gaskets at an unexplained rate, I will likely give it a shot in a future video.

[@colt5189]

@@TheBrokenLife I've come across Lefoo brand of pressure switches. They are like $25. Which is what I plan on going with as it's the only name brand I've been able to figure out as everything seems cheap chinese quality.

[@TheBrokenLife]

@@colt5189 I've used a Lefoo before and it was no different than anything else. If I have to replace another one again, I will probably use a Condor (which is what my new compressor came with and is of noticeably higher quality) and adapt it to fit. The one linked below is probably the most appropriate for smaller compressors: amzn.to/3Tcw3yX

[@cm1133]

Sweet Foxbody behind you.

[@TheBrokenLife]

Thanks!

[@jeremygalloway1348]

I'm not really a mustang guy...but hell yea that fox body is purdy

[@gmickb]

great tutorial!

[@TheBrokenLife]

Thanks!

[@JJJobson]

Mine is outside with a Webber Smoker cover underneath my carport. I don’t use it often but I have had no issues so far. It is at least 5 years old. Maybe older. When it dies I will use it as an auxiliary tank and buy a better one for sure. But for now it is still kicking

[@TheBrokenLife]

👍

[@angeloevangelou918]

I need to know a little more about the relief circuitry, I have made a small refrigerator compressor into an airbrush compressor with a small tank, I would like to know how to connect the relief output to the compressor, how doew it work? what sort of valve it energizes? thank you for your time.

[@TheBrokenLife]

The nylon hose that goes in the bottom of the switch applies tank pressure to a diaphragm that works against a spring. Once the pressure gets high enough to overcome the spring, the compressor shuts off. With all of that said... I have to to officially state that I do not endorse people making their own compressors, or at least that I'm not responsible for anything that happens if they do. 😁 Good luck with it. 👍

[@undergroundoutlet]

I have this exact t compressor and one day it just kept blowing inside of the switch area. Harbor freight doesnt even have this anymore. I just ordered it. Thanks

[@TheBrokenLife]

You're welcome! Good luck with it. 👍

[@dadandkids5028]

I have a similar switch I am trying to install. But I can't get past removing the red button and the black shrowd. Is there a trick?

[@TheBrokenLife]

As I remember, I didn't even have to remove the button on mine as I was just messed up in my thinking. If you think you need to on yours, just pull really hard with some pliers. You can't double break it. 😆

[@andriistratii6180]

I have similar compressor and doesn't build pressure. I already take off head, disassembled pressure switch. Everything looks good. When I run compressor disconnected from tank it suck air and blow. But when I put it back together it doesn't suck and blow from intake.

[@TheBrokenLife]

About the only thing it could be at that point would be the check valve on the tank. If the valve is obstructed or failed, it will never build any pressure. I would still expect to notice "something" at the intake, but... Who knows? That's my best guess, anyhow. Good luck with it. 👍

[@Joe-rr3ip]

I've had mine ,Central Pneumatic, for twenty years, no problems

[@TheBrokenLife]

Count yourself among the lucky.

[@galenb8779]

Can someone tell me why the switch in the link from Amazon says 240V... should it not be 120V?... I've looked at several and they all say 240V.

[@TheBrokenLife]

The descriptions should, but don't, say "up to 240V" not just "240V". If you look carefully at the top of the cover, it actually says "Max Volts300, Amp20, Max Bar 12 - PSI175". For us, the only thing there that really applies is the 20A, since a 120V configuration will pull the most amperage. US household 120V electrical outlets are typically on circuits of 20A or less, so the switch is more than adequate for the task. And just for reference, the rating of 175PSI shouldn't apply to us either as the compressor isn't rated for that. The switch should be factory adjusted to more like 120-130PSI. If your switch is _not_ shutting off around there, it either needs adjusted or replaced.

[@cm1133]

What brush on air line thread sealant did you use on the fittings?

[@TheBrokenLife]

Teflon pipe sealing compound, commonly referred to as "pipe dope". It's linked in the video description.

[@cm1133]

@@TheBrokenLife danke schone

[@TheBrokenLife]

@@cm1133 Gern geschehen! 👍

[@williamcallahan9411]

Too bad the diaphragms are not available/replaceable. I have a HF compressor that is at least 10 yrs old and i suspect my diaphragm is leaking. Where did you get the new replacement part?

[@TheBrokenLife]

Links are always in the video description. 👍

[@williamcallahan9411]

@@TheBrokenLife I guess i should have looked harder and clicked on the "see more"! I fount 1 fot 10 bucks in the mean time. Next compressor will be a little more powerful with a bigger tank, though i thought of adding a Portable tank that i could easily detach for dual use- xtra capacity and portable air.

[@TheBrokenLife]

@@williamcallahan9411 I share your exact thoughts. The compressor that is putting my HFT into retirement is a little more powerful with a little bigger tank. 😁 Check out the air compressors playlist (also linked in the description) if you want to see the whole story.

[@williamcallahan9411]

@@TheBrokenLife Thanks!

[@TheBrokenLife]

@@williamcallahan9411 Thanks for watching!

[@ianmoore525]

Enjoyed your video. I have what looks like ur new regulator on my fairly new AEG silenced 3hp 60l compressor. Adjusting that screw through the hole beside on/off knob does nothing after 3 to 4 full turns anticlockwise. I think 145 psi is too high. That plastic cover just pulls off the cut out switch? I want to have a look inside.

[@TheBrokenLife]

Thanks! I _think_ that screw just holds the cover on. After you're inside is where you'll find the pressure adjustment mechanism. Tinker cautiously...

[@ianmoore525]

@@TheBrokenLife thanks for taking the time to reply, I didn’t actually see you tighten or loosen up the screw under the hole in the plastic box covering. Just assumed. Thanks, will unscrew it to lift the cover. I’m pretty famous for breaking stuff, lost an arm a good time back but still take a crack at most things. Merry Xmas from Australia 🙃

[@TheBrokenLife]

@@ianmoore525 Sorry about that. I have 3 or 4 various videos were I replace that switch so I may have neglected to show it here. Merry Christmas to you as well! From the other side of the globe, we started without you over here! 😆🎄

[@ianmoore525]

@@TheBrokenLife tried that out and worked a treat. Merry Xmas

[@TheBrokenLife]

@@ianmoore525 I'm glad to hear it! 👍

[@couchback66]

Hi How did you remove the black cover from the top of the pressure switch.

[@TheBrokenLife]

I think there's a hole in the middle of it with a screw. Unscrew that screw and then just pull it off. I remember that sometimes they're tight.

[@couchback66]

@@TheBrokenLife Thankyou for your help👍

[@carlnikolov]

Hey mate. Nice stang. Maybe the on off switch pull up on the knob and maybe a bit of grease around the outer perimeter.. would that help or...?

[@TheBrokenLife]

Thanks! Refreshing my memory... Was this the one with the tight switch? If so, I don't think the switch is rubbing on anything. The snap-action detent is just pretty tight on it. They sort of "snap" on and off and the snap on this one is just a bit tight. That said, I have moved this compressor into retirement so it's not much of an issue these days.

[@carlnikolov]

@@TheBrokenLife Thanks for the reply. I hope you are well.

[@TheBrokenLife]

@@carlnikolov Thanks for watching! I hope you're well also! 👍

[@colt5189]

Do you know how to tell what brands are good quality regarding compressor parts? I'm on Amazon and have no clue what is junk and what is good quality. I'm looking at replacing my pressure switch, and I think I'm going to go with Lefoo brand as that's about the only "name brand" I've been able to come across as everything seems to be generic who knows what. I also want to replace my lever shut off valve, but don't know what brands are good as I see people post photos of theirs cracking on install. I would buy Central Pneumatic brand, which is what my compressor is, but seems they aren't making these parts anymore, or at least not selling them.

[@TheBrokenLife]

I linked you a Condor brand switch that I think would be appropriate for smaller compressors in a separate comment. It's UL and CSA listed, which none of the cheap ones are. Links don't always come through, so email at the address in the description if you still don't see it. For ball valves that you plan to regularly use, pretty much any true name brand will do. But... I'm a big fan of Apollo and Parker. If you have some flexibility and patience, you can get awesome deals on them on eBay as industrial surplus. Parker is the more professional option and is generally more expensive, but you can find the lower tier Apollo stuff at Home Depot and Amazon. For the most part, I believe most Parker and Apollo valves as USA made. For ball valves that you will rarely use, what is cheapest is usually fine. Normally what causes them to fail is junk getting built up on the seals and cutting them when turned. That will happen to an expensive valve too, so, no real point in spend piles of money in that situation. edit: The people cracking theirs are over-tightening them because they're probably not sealing them properly. I have a whole video about how to seal air fittings. It should be in the playlist linked in the description.

[@colt5189]

@@TheBrokenLife I ended up getting a Lefoo brand pressure switch. It was about the only name brand I could find.

[@Jeremy-yr8yg]

High quality replacement parts!😂😂😂😂😂

[@TheBrokenLife]

Only the finest parts that Chinese toddlers can build.

[@OutBoardTink62]

Bought a Sears Craftsman belt driven air compressor in the 1970S when I was a kid. Gave it to my brother and he still uses it as of today. Only thing he has changed was the belts and swapped the tank about 20 years back due to rust with pinholes.The junk thats imported today is sickening and we all buy it including myself,LOL! Its all Planned Obsolescence just about everything today is like that and its not all on cheap items either ...Should get at least 5 years use with these cheap HarborFreight air compressors when used moderately I would say would be fair dont you think ......

[@TheBrokenLife]

The compressor itself has been mostly trouble free for close to 20 years, but I've replaced a lot of those switches.

[@OutBoardTink62]

@@TheBrokenLife Thats a good run could be alot worse.. Pressure switches are high maintenance item on average on many air compressors..

[@TheBrokenLife]

@@OutBoardTink62 For $150 all of those years ago, I really can't complain about that compressor. It was a case of buying the best tool I could afford at the time and getting a lot more than I bargained for.

[@lilgampla]

Anyone know the size of the unloader tube & fittings, mine keeps blowing out

[@TheBrokenLife]

I think mine is just 1/4"/6mm.

[@lilgampla]

Just measured mine comes out as 1/8 on the tank to regulator

[@lilgampla]

Update get you some 1/8 npt by 3/8 od push in fittings and some 3/8 pipe a.co/d/gGGmdWv 1/4 will hold but the bigger pipe should allow the air to flow better 1/4 will pop out fitting or break pipe

[@TheBrokenLife]

@@lilgampla I'm not sure if I'm following what you're saying. If you're just talking about the unloader line, there's no reason to concern yourself about how it performs as long as it does. Its only job is to relieve pressure on the cylinder head of the compressor so it's easier to start when it cycles again. Air doesn't flow through it into the tank.

[@tarstarkusz]

I would be blaming myself if the same part kept failing. Nice job.

[@TheBrokenLife]

I'm not sure how much I could influence the life span of that diaphragm. It did cross my mind to try to buy higher quality replacement parts, but the option of replacing the entire compressor won.

[@tarstarkusz]

@@TheBrokenLife I'm not saying I think you did something wrong. I would just have a natural tendency to blame myself, even though I knew I was buying cheap parts. Just a natural self-doubt.

[@TheBrokenLife]

@@tarstarkusz _Always_ blame the equipment. We're perfect! 😆

[@bsrcat1]

The switches are preset to 110psi because the pressure relief valve on harbor freight tanks are set to 120psi. I've had the exact same compressor for 20yrs. I've had to replace the pressure switch 2x. Of course my compressor has moved seven times and has gotten knocked around. The last move broke the switch cover off... I'm just now getting to the point where I need to replace that because I'm getting pissed off with the zip ties🤣

[@TheBrokenLife]

I've had several of these switches and I don't think any two have ever been set the same... 😆 Normally a bit closer to 120 though.

[@bsrcat1]

@@TheBrokenLife did you change your relief valve? Mine have all pretty much been dead on. My pressure relief valve always been dead on. The minute I even get close to 120 or if a truck rolls down the street it pops🤣. I tried to adjust it up when I first got it. Pssss 🤣 i have made small adjustments when replacing the switches Psssss🤣 So as long as I get to 110 It's happy and i'm happy. 😁👍. Same compressor as you have, bought it used, had it 20 years, on my third switch. The first time I replaced the switch I didn't even need to. It wouldn't start and I didn't know about the thermal switch reset 🤣. Now that threw me for an all-time loop. That was like year 8. Great video by the way 😁👍

[@TheBrokenLife]

@@bsrcat1 Thanks! I'm glad you enjoyed the video! 👍 Hummm... I looked into it more deeply and it seems the owner's manual is calling it out as being a 115psi compressor and not 125 like I would have swore it was. 20 years is a long time to remember what it said on the box it came out of. 🤣 So, your logic stands up. Now I'm curious if my valve would pop at 120 as well... I retired this compressor and replaced it with a model that run at 155 so I could force feed it a bit and see what happens. 😅

[@CantKillMe]

-you could try this out and see if it will work

[@TheBrokenLife]

Try what out?

[@CantKillMe]

@@TheBrokenLife sorry forgot youtube dont like links may need to get a coupler for it

[@TheBrokenLife]

@@CantKillMe It seems sometimes they do any sometimes they don't. I thought about putting it on a hose whip and getting it off of the tank, thinking maybe less vibration would be nice, but then I decided I don't care _that_ much about it. It's going into retirement in a few weeks and we'll be moving on up to the DeWalt.

[@CantKillMe]

@@TheBrokenLife ok cool hope it works out on the new DeWalt

[@Fordcertian]

Use both tanks on your main compressor

[@larryjohns8823]

The problem with all chinese rubber parts is they seem to use NO ozone inhibitors. This causes the rubber to not last.

[@TheBrokenLife]

That could very well be true. In my case, actual chunks of rust coming out of the tank seem to be playing a role as well.

[@iwcmc]

Baur air compressor parts service

[@fourbyfourer]

I am sooo sick and tired of buying ANYTHING due to EVERYTHING is of poor quality!! It's so annoying when trying to fix something and parts are junk. Any new tools or equipment only lasts till the warranty is up.

[@TheBrokenLife]

The fascinating part of this stuff is that it was all really low quality the day I bought it and somehow they've managed to reduce standards even from that point. 😂 That said, I don't think HFT even sells compressors this size as cheap as mine anymore. It appears the nearest competitor is now roughly twice the price. I suspect the quality hasn't doubled, though...

[@fourbyfourer]

@@TheBrokenLife Nope, I bet you're absolutely right about the quality hasn't doubled lol.