3 Reasons for an Air Compressor Leaking Pressure Switch 

Awesome! You settled an argument and, answered all my questions even without me having to ask. Thank you so much.

If you have replaced the check valve and replaced the pressure switch and still have air leaking through the unloader valve on the pressure switch, then you may need to make a slight adjustment in the clearance between the pin at the end of the unloader valve and the paddle switch. I had this problem with a switch on a Senco 0968 compressor that is like the black one in this video. The pressure switch has a small lever or paddle that pushes a pin at the end of the unloader valve when it shuts off. If the unloader valve leaks air after the compressor shuts off and keeps bleeding the pressure down to zero through the unloader valve, check the adjustment between the pin and the paddle. There is a nut just behind the pin on the unloader valve that offers some adjustment and there is a screw that secures the unloader valve to the pressure switch housing that also offers some adjustment. The adjustment needed is slight but it can correct the leak and allow the compressor to hold pressure. Worked for me.

Thanks for the video! You helped me find a bad check valve on my 30+ year old Craftsman 4hp compressor! First I changed the pressure switch, which wasn’t the problem. Now waiting for the new check valve to arrive.

Thanks! After many videos yours is the one that answered my question.

If you have a general air product and you've changed out multiple pressure switches and you can't figure it out! it is at the end of this video thank you so much sir respect

Very helpful video thank you

Thanks, old guy here no clue. Vid explained why #3 my chevk valve was the problem. The valve turned out to be serviceable, cleaned it out ,all good.

Thanks for this informative video!

You answered my question perfectly. Mine was leaking only when the compressor Was running from underneath. I replaced the original switch about 3 years ago and bought a cheap replacement. Go figure. Thanks again.

I need a check valve (compressor only leaks from the switch when off) for a Craftsman Sears Craftsman 919.167320. What part number do I look for on your website? Does it come with a removal and installation guide? Thanks.

Hi I have a wolf professional 90 litre . It is brand new only used it a few times and my switch is leaking when I pull the switch up to switch it off. Is it normal for them to go wrong as soon as that??

Sir I have a husky air compressor where can I get a replacement one ( valve switch is where it leaking)

I replaced the pump on my Campbell Hausfeld 80 gal/175psi, 2 stage pump with has a check valve on the hose between cylinders. The new 2 stage Harbor Freight pump 145psi has no check valve. I lowered the max cut out pressure 3 turns CCW on switch. Ran pump up to 140psi and shut off. Unloader valve releases air when shut off until pressure is lowered to around 120 psi. Is this just fine tuning of the switch adjustment or do I need to add a check valve?

So I have a question I replaced the check valve and the unloader but my switch still leaks air once it gets up to pressure i can see it activate the loader once it gets pressure in the tank about 80 psi and stays on till around 20 then it shuts off

I have an Ingersoll Rand, single stage, 5hp, 60 gallon upright compressor. It just started leaking under the pressure switch. Max pressure is 125 psi but when it reaches about 100 psi the leaking stops. I replaced my check valve but this did not solve the problem. Any other suggestions? Do you think my pressure switch is bad? Thanks.

if my air compresor pressure switch does not have cut in pressure can i change it with another pressure switch witht cut in an cut out? It is like this from factory.

Hi. Is the ckeck valve aka relief valve?

I just had problem 2 you said needs a complete new switch, I took the valve out cleaned it and works fine now.

On a couple of occasions I had to lightly sand and oil the side of the rubber stopper in my check valve when leaking after pressure switch shuts off. The rubber seems to expand and get stuck in the housing nut/cap. It works fine as long as it slides easily within the valve.

Great video! it helped

Could it also be the regulator manifold?

fantastic help.. thank you! :D

Wow! Very informative video I did not expect to get all my answers on RU-vid let alone one video. Thank you for making this!

Nice video! I had (have) problem 3, the thing is I replaced the check valve and still have the same issue... Any clue what happened? Thanks in advance

I have a leak on the under side of the pressure switch it's the valve stem that's leaking. Is there a way to seal that off?

Thank You!

Thank you sir

Thanks. Very helpful. I will be removing my check valve.

Hi when I first got my 150 psi compressor it would fully pump to 150 psi for maybe 2 months. Now when it pumps up it maxes out at 135 and cuts out. Which part should I be looking to purchase? Thanks

I have problem #3. If I turn off the compressor or, it hits the `150PSI max and shuts off there is a valve inside the switch that pops open and bleeds down to about 80 PSI then the valve closes and compressor cuts on and repeats the cycle. It is interesting that when I turn off the compressor via the top switch it makes the valve within the switch open and bleed out. My Sears parts list has a Tank Safety valve and a valve bleeder. Please let me know which you feel it is or both that need to be replaced.

Nice vid.. really helps.. thanks!

My compressor constantly Runs will not build air pressure is the adjusting value the problem ?

Thanks for such an informative video. All hail the Algorithm

CS mine builds air fills the tank and leaks out of the oil fill plug hole help !!!!!

Problem #1. Thanks mate saved me a lot of f**king around

Nice

I’m having the same problems , I want to replace the check valve.its just difficult to get to it , it’s under the pump and the motor .

2:58 I Thank you very much!

I just replaced my precious switch on my campbell house field compressor. I turn the compressor on and it fills up to a 120 P, S, I, then shuts off.....then the unloader starts leaking until the pressure drops to 100 psi then it stops leaking????????

How about piston rings being bad and leaking from pump exhaust. I can think of about 12 reasons they leak.

It could chenged the u/l valve and diaphragm also,and if yes you want sell your whole pr. Switch than its also fine

Excelentemente aka super excelent separate the words excelente mente becomes excellent mind i Like, OLE!

It only leaks air when you flip the switch to turn off compressor what could be the issue

I have a compressor rated for 125psi but it won't build past 98 PSI. Could this be a leaking pressure switch?

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Mines leaking from the diagram housing.

check valve can cause it to leak when running or when it is off. if 2 and 3 can equal the air coming from the unloader then 1 can also as in this case 1 = 2+3. this video caused me to disassembly my pressure switch as it constantly leaked. well when i opened it up i noticed there was nothing wrong with it. now i have to put it back together. and no it is not that hard which is another thing this video got wrong.

I have very differend unit.. (Strong Line.) 😳

My pressure switch unloads air when reaching the max pressure. Is it normal?

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My compressor will build up air but once it reaches Max pressure it'll leak air until compressor kicks back on, over and over again. I have to unplug it in "on" position to hold the air in. Once it turn to "off", it'll leak again

I have problem #3 so I bought a whole new switch and still having the same problem

As I’m new to this. I bought a used compressor that had a three phase motor and I later replaced it with a single phase. Do I need a different pressure switch?

Put up with it for years now replaced the switch and now realize it's the check valve if you're correct..

it makes no sense what he is saying .if leaks when its on ,of corse will leat when its off ,what the hll

I didn't read through all of the comments, but it seems that you never discussed how to determine that it is the compressor switch that is leaking.