Compressor won't shut off

[uamsclay]

I bought a lacrosse 120 machine from a yard sale, fixed coin mech, fixed lights, added freon.  Stocked machine pretty well and it cools great but the compressor will not cycle off.  I have tried twisting the dial to several settings and that doesn't help. Currently it is on setting 4 and right at 40 degrees.  I have seem others on this site that have had issues with a temperature gauge not shutting the compressor off, is that what I am dealing with?  If so what are my steps to fix it?  New to this, so I'm thankful for any help or advise.
Clay

[collecture]

Either a wiring issue or bad T-stat - condenser fan and compressor should run concurrently 2-3 times per hour and the evaporator fan runs continuously.

[Yarochrehc]

Try this first. Unplug the cooler, take one wire off the thermostat and isolate it so it won't short out when you plug the cooler back in, and see if the compressor runs or not, if it runs you have a wiring problem, if it doesn't it could be the thrmostat.

[loman4ec]

Since the machine is running at 40 degrees constantly it sounds like an under charge to me. the tstat may be fine. The compressor will not cycle if the machine can not cool down to the correct temp. If you turn the thermostat all the way until it clicks does the machine shut off?

[uamsclay]

we added a little more freon.  the machine will shut off somewhere between the lowest setting and the actual "off" setting.  it now seems to be trying to cycle off, but then will cycle back on within 30-60 seconds even when on a setting or 2 or 3.  i haven't tried to unlplug it and isolate the thermostat yet, that will be the next project.  basically it is running all the time, except it will shut off for about a minute every hour then turn back on.  thanks for the ideas, i will keep you updated and please feel free to keep throwing out ideas.  also, it seals pretty well but i am trying to improve that as well. 
clay

[collecture]

Usually (after temp has been reached) the compressor will start up and run for 15 minutes....shut off for 15-20....start up for 15....