Compressor fan runs all the time

I have recently come in posssession of a couple of coke and pepsi machines. I manage to get one up and running before the winter came. It is a vendo v312.
The machine was working great for a couple of months until recently. Now the compressor fan continually runs. The overload clicks every 30 - 45 seconds but the compressor won't come on. The unit kept the contents nice and cold when it was working but now it won't keep anything cold. I have unplugged it for a couple of days and when it was plugged back in it worked perfect for a couple of hours, the compressor would come on. Then after a couple of hours (after it got the machine nice and cold) the overload would start clicking on, the compressor fan would continually run but the compressor would not start up again. The compressor unit is warm.
I am new to this and from what I have read on this site it seems like this is the place to get help. Any suggestions would be greatly appreciated, as I can see I am going to need assistance when I work on my other machines.

[johnieG]

Off hand I'd say the compressors low on refrigerant, this would cause the compressor to over heat & draw too much current, less likely would be a defective overload, but it's the cheapest place to start troubleshooting. so I'd try a new overload breaker first, & then have the pressures checked out
by a refrigeration service tech on site, or if necessary you can just remove the compressor/assembly & brng it to them
also try giving Eric @ global compressors a call & see what he thinks, he's the man! look under the suppliers section or click on his banner-ad...JohnieG

Thanks for the advice. I tried a new overload protector and same problem so most likely it needs to be recharged.
Is this something I can do on my own or should it be done by a technician. I live in a very remote community so we are a little short on technicians.

[johnieG]

Now we're getting serious! Well that depends, you'd need a set of gauges for the refrigerant your using (listed on the compressor info tag.), a can of refrigerant, and a tapping connector, unless there's a recharge fitting on the compressor lines somewhere, (however, it must be a low-side pressure ) fitting, and unless your really, REALLY sure you know what your'e doing it might be best to call someone who does, hate to see you get injured bursting a line or something. or you might be able to source a used/refurbished replacement deck (the whole compressor/evaporator assy.) out of a simular unit, from a local vending machine shop
or pull & take/ship it to a local shop and/or Global compressors they can give it the "once-over"  & make sure everythings OK . also theres companys on Ebay who sell used late model machines that might be able to fix you up too.

[cvb141]

Disconnect the evaporator fan motor and let the compressor run a little while and the evaporator should frost over completely. If it only frost a portion of it, then it may be low on refrigerant or a possible restriction, which either one can damage the compressor if allowed to continue to run. The compressor could be binding enternally and going out on overload after running a while. You can check the amp draw and compare it with the name plate on the compressor if it has the RLA. If it has only the LRA then you can divide it by 5 then by 6  and this should give you a close range of what it should be pulling amp wise. What area of the country are you in?

Jerry

[globalcompressors]

Hey Bud,

  If the cooling unit is pulling down to temperature when you first start the unit up, after sitting, there is nothing wrong with the charge. If you replaced the overload and are still "tripping" out, the compressor windings have lost  resistence. It's probably between the common and the run winding. Get an amp meter and check the leads, while running, and the reading should be between 2.5 and 3.5 amps, per leg. If it's over that check the wiring and all your connections for any problems, loose connections, etc. Also check the fan motor and make sure it to is running at speed. Sometimes fan motors, when they heat up and are going bad, will tend to slow down thus reducing air flow across the coil and raising the head pressure on the compressor. Higher head pressure, higher amps, more load on the compressor. You get the point. If all else checks out, then the compressor is on it's way out.

Eric