I turned on the machine but the compressor did not go on

If your Bunn Ultra 2 slush machine's compressor is turning on and off immediately, not allowing the product to freeze, there could be a few possible causes. Here are a few things you can check:

1. Check the thermostat: Make sure that the thermostat is set to the correct temperature and that it is functioning properly. A faulty thermostat can prevent the compressor from turning on.
2. Check the compressor relay: The compressor relay is responsible for turning the compressor on and off. If the relay is faulty, the compressor may not stay running. You can check the relay by using a multimeter to test for continuity across the relay's terminals.
3. Check the compressor motor: The compressor motor could be faulty and not able to start or stay running. You can check the motor by using a multimeter to test the winding resistance.
4. Check the condenser coils: The condenser coils could be dirty or clogged with dust, which can cause the compressor to overheat and shut off. Clean the condenser coils with a brush or compressed air to remove any dust or debris.
5. Check the compressor's oil level: If the oil level is low, the compressor could be damaged.
6. Check the overload protector: The overload protector is a safety device that is designed to protect the compressor from damage caused by excessive current. If the overload protector has tripped, the compressor will not start or stay running.

It's worth noting that a compressor not staying running could also be caused by a more complex issue

What breaker? The breaker for the condenser? Likely have a compressor shorted to ground or drawing locked rotor amps. Easiest way to tell is make sure breaker off, unhook compressor wires from contactor. Turn on breaker and turn on machine. If the breaker does not trip, obviously problem with compressor

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could be one of many problems. the most common is the 4 minute timer that keeps the compressor from short-cycling. open up the right front panel and the timer is gray and almost circular and near the top of the inside. with the machine off, unplug the 2 long, thin blue wires that go to the motor of the timer, but do not unplug the orange, light blue and brown wires going to the timer. now turn the machine on and using a flat head screwdriver, turn the slotted head in the front of the timer clockwise until the compressor turns on. now the timer is disabled, and the timer isn't that necessary. if you still have a problem and all switches are on, you may have a blockage in the high side refrigerant line and the higher pressure triggers the compressor to shut off

could be any number of things: mixture being too rich (add more water), timer is off (reset defrost timer on side), 4-minute timer is not turning on compressor (inside right front panel. unplug thin blue wire harness, turn middle screw until compressor turns on), the refrigeration solenoids (is there a click from the back when you turn the switches on), does the compressor turn on, does the fan turn on (if there is no air flow, the overpressure sensor will turn the compressor off), or maybe there is a leak. if it is the last case, you will need a professional to take a look at it.

If your machine is equipped with a humidistat it could be faulty and not sensing the humidity level accurately.

Is the compressor overheating when this happens? Feel the top of the compressor when this is happening and tell me if the top of the compressor becomes extremely hot to the point that you cannot keep your hand on the compressor. Reason I ask you to do this is that it is possible that the compressor is short cycling because of a defective start relay and/or run capacitor. Let me know if the compressor is overheating of simply turning itself off. I will post a service manual if interested but would like to e-mail you the service manual for your Hoshizaki KM-255BAH because of copyright issues. You may contact me HERE if you like. Thanks Sea Breeze

Check for leaks all over the machine. Possibly the O ring on the drain valve is damaged. If the machine is oil-less, the big rubber O ring on the piston could be worn away.
When the machine is turned off can you hear air leaking from anywhere?

What your hearing is the KliXon thermal overload tripping. The compressor is not starting and the thermal overload is trying to protect the compressor.

This can be caused by 3 things.

1. A locked rotor on the compressor. (bad news)
2. A failed PTC relay on the compressor
3. A failed run capacitor.

Usually a PTC relay and a run capacitor will bring it back to life unless the compressor is actually seized.

Thanks for using FixYa.

Kelly

that know your turning is the defraost timmer
itg should turn the machine back on in like 20 min
if its not turning the machine back on then its bad

something not right here ,firstly why didnt you just renew the clutch instead of a complete compressor ?? secondly do you have a machine to recharge the system and if so are you using it correctly ,the reason i ask is because in the machine the low and high pressure pipes are interconnected in the body of the machine so yes it would show these pressures.When refilling a car once machine has weighed the gas leaving the bottle shut off the red line and start engine leaving the blue line connected ,run engine at 2000rpm with A/C on full for about 3 mins to draw the gas in from the machine .Then close blue line and and do a recovery to see how much gas was left in the machine.Also did you put compressor oil in when you re fitted the compressor about 100cc is enough ,this is better put in directly into compressor ,then vacumn to about -750mg or a stage one vac pump and omit the oil recovery cycle .When running the air temperature coming out should be about 7.5centigrade is good but some cars will drop to 5C anything below 9C is ok ,and forget to clean out pollen filter