Sub Zero Ice Machine Operates, but Will Not Make Ice – How to fix? by

How to Use the Troubleshooting Guide 3 The list below indicates how the Troubleshooting Guide is arranged. Identify the description of the problem that the unit is experiencing from the list and go to the page indicated. To the left of the problem description is a letter. Locate that letter in the left column of the Troubleshooting Guide. The center column will identify the possible causes for the problem. And, the information in the right column will explain what tests to perform in order to determine if what you are checking is the cause and/or what action to take to correct the problem.

Problem Posible Cause TEST / ACTION
Ice Machine Does Not Operate Improper Ambient Temperatures Ambient air temperature minimum = 50°F (10°C), maximum = 100°F (38°C) for models UC-15I and UC-15IP; 110°F (43°C) for models UC-15IO and UC-15IPO. Advise customer. NOTE: Check control board light to see if ice machine shutdown on over temperature limit (control board light will flash rapidly).
Improper Water Pressure Water pressure must be 20 – 80 psi (1.4 – 5.5 bar). Advise customer.
No Water in Water Trough a. Water supply is off. Turn water supply on. b. Check water supply line for kinks or restrictions. Replace defective supply line. c. Check water filter. Replace if clogged. d. Check screens in water valve for obstructions. Clean screens or replace valve. e. Check for loose or disconnected wiring to water valve. Repair bad wiring. f. Check water valve integrity / operation. Replace if defective. g. Check trough for leak. Reposition/replace trough. h. Check standpipe. Reposition or replace.
No Water Spray from Spray Nozzles a. Check for blockage in spray nozzles. See Maintenance, Cleaning and Adjustment Information section of service manual. b. Check trough for leak. Reposition/replace. c. Check for loose or disconnected wiring to spray pump. Repair or reconnect wiring. d. Check operation of spray pump. Replace if defective.
No Airflow Through Condenser a. Check for obstructions in vents of kickplate. Move/clear obstruction. b. Check condenser. Clean if dirty. c. Check for loose or broken condenser fan blade. Repair or replace blade. d. Check condenser fan motor wire connections. Repair or reconnect wiring. e. Check operation of con
Hot Gas Valve Stuck Open Check operation of hot gas valve. Replace valve and drier if valve is defective.
Liquid Line Thermistor Fault (Disconnected, Open or Misread) a. Check connection at board. Reconnect. b. Check for 30K – 33K ohms at ~32°F / 0°C or 8K – 12K ohms at ~77°F / 25°C. Replace if defective. NOTE: A slow flashing light at control board indicates thermistor open or disconnected. A rapid flashing light indicates temperatures exceeded 170°F (77°C); look for cause and/or check thermistor resistance.
Compressor Electrical Fault a. Check compressor electricals for loose or disconnected wiring. Repair or reconnect. b. Check operation of overload and relay. If defective, replace.
Sealed System Fault a. If power is at compressor and electricals are good, but compressor will not run, replace compressor and drier. b. Inspect sealed system for leaks, restrictions or inefficient compressor by observing frost patterns and feel tubing for irregular temperatures. Repair or replace components as needed.