Mastercraft 5-gallon won't cut-off

by Sabin

HI, i have a Mastercraft 5-gallon air compressor that just wont stop building air into the tank, to the point that the Pressure Relieve Valve does its job and let the extra pressure go out.

Then the cycle goes on again.

I cant see to find the pressure sensor, is there such a thing on that Mastercraft?

Manual says the power (red) switch IS the pressure switch.

BTW on that switch : - means OFF and O means ON ?


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May 08, 2017
Cylinders and switches
by: Bill

I don't know for sure what the cylinders you refer to are, but I suspect they are capacitors. See the page on capacitors on this site for detailed explanation of what they do.

You don't need an OEM pressure switch, any one with the same set points that you can install will do. If you Google compressor pressure switches you will find many sources. Obviously look for one that appears the same as the one from your compressor.

Good luck.

May 08, 2017
by: sabin

Hi fellow, looks like its the pressure switch, right?

Problem is to get one fast. I need my compressor to finish some jobs.

Will try to get one.

Is there a way to check the old one to be sure its the problem? One of two plastic cylinders (with wires connected to them) bracket just broke and let the cylinder hang onto the motor. Seems to work thought. Are those cylinders related to pressure?


May 08, 2017
Mastercraft air compressor
by: Bill

Sabin... nope, I'm not in Montreal. That's my ISP.

Re: pictures, start a new comment, add up to four photos, and tell me in the comment that they are for this post, and I'll move them.

Please see Doug's comment about where the pressure switch is.

I simply Googled AIR-RITE 105/135 switch, and found many sources, if this is the one you wish to replace.

May 05, 2017
Mastercraft 5-gallon
by: Doug in

What Bill said.

But I'd venture to say if you look at the parts diagram near the back of the manual, you'll find that what you think is just a power switch - IS. (part 19) - if you have what I think you have.

And the actual pressure switch is mounted on the lower tank, part 31.

Conventionally, many switches are labeled "0" (zero, or off) and "|" (one, or on).

May 05, 2017
Follow-up on Mastercraft air compressor
by: Sabin

Hi Bill, i am in Montreal too. Here are some pictures. I am wondering if i havent ruined the pressure switch by NOT emptying the tanks as suggested after work. It probably sat with pressure for a month!

And yes, there are 2 black wires that goes to the switch:

- one directly from power cord
- and one coming from the big red power switch

The switch itself says:
AIR-RITE 105/135

The compressor is a Mastercraft 5-gallon double tank. Stick says CSA Intertec.

Where can i order a new switch?

Hope that helps!


PS ; How do i send picture?

May 04, 2017
Mastercraft won't stop running
by: Bill

I don't know the model of your Mastercraft air compressor, and without a picture, it's pretty hard to figure out what is what.

However, I don't believe that the Red Button (the ON/OFF switch) is the pressure switch, regardless of what the manual says.

What ON/OFF buttons commonly do is turn the power on and off to the pressure switch, and it's the pressure switch that controls the electrical flow to the motor circuit.

So, provide a model number, send a picture which we'll add to this post (start a new comment and you can add up to 4) or pull the cover off, with the power plug out of the socket, and see where the wire goes from the ON/OFF switch. I'll bet the black wire goes to the pressure switch which will be inserted into the tank.

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