AirMaster won't shut down on its own

I have an AirMaster upright 220 volt Compressor that I bought new in 1982. It has performed flawlessly for me until yesterday, I was in my shop working on another old tool, when the compressor started automatically, I thought it was running a bit longer than it usually does to re fill the tank from line loss. but then the pop off safety valve let go. I was right next to the fuse panel so I just reached up and shut it off. (the compressor continued to run when the pop off valve let go so I had all kinds of noise around me) Im guessing that the pressure switch has seen its day, and I should replace it, but the company has gone out of business several years ago. Any clues where I can get a pressure switch for it? Airmaster Model 5186 Serial 602 wired for 220 volts, switch plumbed into the side of the tank. Single stage, twin cylinder Stationary ASME Receiver mounted. Switch has a small handle on the side to turn it off and on, wires coming in from house ;power on left side, wires going to motor on the right side, and a small tube coming down to it from the compressor itself. It also has small pipe going to a guage to indicate pressure in the tank. It has a part number listed for the switch CW-1025

 

You can use almost any pressure switch. The one went out on my compressor at work and I found a replacement on Amazon.

 

Is that Airmaster compressor blue ? If yes.... it's probably a Quincy.
They're still in business but like Dane mentioned any pressure switch will work.

You need to confirm if your current pressure switch has the unloader connected to it.
You need to make sure the amperage rating is large enough for your motor.

 

Thanks for the replies! I was pleasantly surprised after I did this post to DIY I googled the Part number and came up with a campbell hausfeld SKU that is available widely. I picked out an exact duplicate of mine from a distributor in California , with the exception of the wire connections. (Same number of connections just relocated on the switch slightly) I was more worried about the plumbing connections. If the unloader is the small pipe that goes up to the compressor's pump, it has that too. If the unloader is the pop off valve, there is a plumbing port for that as well.

 

The unloader is the little pop-off valve that opens when the switch shuts off.

 

I know that there is an unloader on the original switch, I hear it unload when the switch shuts off. I would assume that the new switch would have one too, or am I on the wrong track?

 

I don't know what switch you are considering but many do have an uloader. A look at the specs for the switch you are considering would confirm. If the switch has a fitting on the side it likely means it has an unloader but again read the specs before purchasing. Most switches have multiple ports on the bottom, you use one and install plugs in the others. Do not confuse the ports on the bottom which are the main pressure sensing ports with a fitting on the side for the unloader.

In this photo you can see the unloader on the side of the switch.

 

Well I definitely have one of those on the original switch. If my new switch does not come with one, I guess I will be trying to use the one I have, or getting a new one lol

 

The Pressure Switch came today. The tech at Pacific Air Compressor warned me that in 30 plus years Campbell Hausfeld changed the switch slightly. The change is where the Line wires and the Motor wires mount on the switch.
The Old Switch had a like a step in it. If you face the switch the high side of the step is toward you, and the lower step is close to the compressor tank. the red handled manual switch is to the left and close to the high side of the step. Before I make a wrong guess as to where to put the wires, by color I just thought you guys might know. (The old switch, same size, same pipe and wire mount holes etc) Had two line wires come in and mount the red wire on the top left side of the step. the black line wire mounted on the lower left side of the step. the WHITE LINE wire is mounded to the switch case for GROUND. The Motor Wires were mounted on the right side with a white wire on the top step, and a black wire mounted on the bottom step right side.
The NEW switch has marked for BOTH line wires to fasten to the connectors on the TOP step but wire color is not noted. the MOTOR wires (Just two) black and white mount on the lower step in the switch but again are not marked by color. I THINK if I reverse something, something may run backwards, but I do NOT want to smoke a brand new switch. Any clues or diagrams you can send me, I am almost there I think! My Switch looks just like the one you sent me in a previous post.

 

Since the motor is 240v...... there is no polarity.
Either power wire can go on either terminal. Same with the motor wires.

 

Your're not just saying that to make my day, are you? LOL (Thank you!)

 

If the wiring is on the wrong terminals your air compressor will be sucking instead of blowing.

 

Lol I guess I got lucky. I've got more compressed air than sparks and smoke. thanks again for your input!