Manitowoc Ice Machine not making ice

[idoseadoo]

Hi guys, I bought a used Q0212 under-counter ice machine from 2008.  The guy said it fills up with ice, but stops making it. The compressor kicks on, but doesn't get cold enough to make ice QUICKLY. It'll make ice in the 1h the machine gives it before it automatically goes into dispense mode. The bridge never forms enough to touch the sensor. The partial sheet quickly melts off and triggers the drop lever which sends it "freezing" again. I noticed that the bottom of the evaporator makes more ice than the top, and the evaporator with water cascading over it gets down to about 23F. The water works are fine, even better than my other unit since someone actually restricted the flow of the motor by pinching the tube at the top. I get a nice consistent flow over all the cubes, but not so much that it washes them out or splashes all over.

I put gauges on her and with 80F ambient, I'm seeing that the high side goes from 225psi up to like 275, which is where the fan comes on and off. My suction goes from 55 to 75, consistent with the high side. The previous owner set the fan to continually run, bypassing the high pressure switch, maybe because that switch is wrong. According to the book, my fan is supposed to come off/on at 200/250psi respectively. Not sure this makes a huge difference as my suction never seems to get down to the 30psi it's supposed to be at.

What should I check next? There are some checks in the manual, like verify that the suction temp is this discharge is that. Do I measure those at the compressor?
What subcool/superheat numbers should I be looking for, and do those change with ambient temp?

[InfinitudeMECH]

Right of the hop I'm inclined to say you have a refrigerant charge issue with what your saying.... non uniform ice across evap.    What is the metering device on this unit?  Those machines are critically charged, they need ever oz of refrigerant thats in them.

In the future, if you do have to hookup gauges to a critically charged unit, find gas retention access valves and use just gauge dials to check the charge. 

I would blow off the residual remaining refrigerant and weigh in the rated charge.  Test the system from that bench mark. 

 Condenser fan cycling is really there to keep the head pressure up during harvest.  This wouldn't cause ice production issues, it would cause harvest/release issues if anything.     

even before you do any of the above, is the discharge on the compressor hot during operation?