by Dave Hershberger
(Burr Oak, MI)

My compressor had been working fine except a bit sluggish coming on at times during this cold weather we’ve had here in S.W. Michigan. Now it won’t start. I bought it new and it hasn’t had heavy usage.

In any case I have taken a plastic motor cover/support off to try to get to wiring to check current into compressor and out to motor. You can’t see the ends of the wires at armature to check current there coming from the “pressure/Switch” housing wires.

I am uncertain how to remove the pressure switch housing (plastic cover) to get to the point where the wires connect and go to motor and capacitor. So I can check current there. There appears to be continuity on the large white capacitor on top of the armature area of the motor whether the switch is on or not if that is of an concern as it relates to starting the motor.

Any tips on this issue would be greatly appreciated as I can’t seem to locate a service manual on the compressor and the user or parts manual does not show any parts for the switch or how to remove housing cover ot switch button to check electric or clean the switch or anything inside the unit.


Alton compressor current
by: Doug in

Easy way to check current:

Get a set of heavy duty plug/sockets.
Use 10 or 12 gauge wire about six or eight inches long and make a short “extension” cord, but break out the black hot lead (or either one in a 220v set up). Put your clamp style ammeter on that.

Typically, the cover on the pressure switch is just a single captive screw at one end of the cover. the cover just flips off when that is fully loosened.

I notice two different versions of the switch on two alleged “Alton AT01204-6”.

A manual is available on-line in PDF format.

Good luck.


Additional info
by: Dave Hershberger

I have since discovered the pressure switch is bad and needs replaced on this Alton air compressor. Does anyone know if there is anywhere online that sells Alton compressor parts. I haven’t found anywhere else but Alton Industries to date.

Dave, likely you won’t need an OEM pressure switch, but I don’t know for sure, as I do not know the one that is on your compressor now.



Alton pressure switch identification
by: Dave Hershberger

The following is info I found stamped into the outside of the pressure switch cover.
Amax 20
Barmax 12.5
PSI max 180

There is a dial stamped on the inside top of the cover but I do not know what if any significane the numbers are. There is an arrow with a one on one side and a zero on the other side ant the arrow point is towards a number 8.

There appear to be 4 small bolts that fasten the switch to the housing, there is a red on off button on top with a single screw on top to hold the switch cover onto the switch assembly. There are of course two sets of white and black wires cominto and going out from the switch and this operates on 110V current.

Is there any other info I need to be able to identify and locate the correct pressure switch, or to see if an aftermarket switch will fit and work properly for this compressor?

Assuming that your pressure switch is used solely for turning on your air compressor motor when the tank pressure drops to cut in, and shutting it off again when the tank pressure reaches cut out, and you get one with similar cut in/cut out pressure (or is adjustable) settings, has the same voltage handling capability, actually fits on your compressor, and operates the unloader valve correctly, then any non-OEM or OEM brand that meets those specs will do.

I was not able to identify the pressure switch you have from the information provided.

There is a page about how to buy a new pressure switch on this site, and using that page, you might enough guidance to acquire a new one.



by: Doug in

“There is a dial stamped on the inside top of the cover…”

That is just a time and date stamp for moulding quality control.

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