ICE MACHINES Q-Model Service Manual

Section 7Refrigeration SystemSAFETY LIMITSGeneralIn addition to standard safety controls, such as highpressure cut-out, the control board has two built in safetylimit controls which protect the ice machine from majorcomponent failures. There are two control boards withdifferent safety limit sequences. Original productioncontrol boards have a black micro-processor. Currentproduction and replacement control boards have anorange label on the control board microprocessor.Safety Limit #1: If the freeze time reaches 60 minutes,the control board automatically initiates a harvest cycle.Control Board with black microprocessorIf 3 consecutive 60-minute freeze cycles occur, the icemachine stops.Control Board with orange label on microprocessor.If 6 consecutive 60-minute freeze cycles occur, the icemachine stops.Safety Limit #2: If the harvest time reaches 3.5minutes, the control board automatically returns the icemachine to the freeze cycle.Control Board with black microprocessorIf three consecutive 3.5 minute harvest cycles occur, theice machine stops.Control Board with orange label on microprocessor.If 500 consecutive 3.5 minute harvest cycles occur, theice machine stops.Control Board with Orange LabelWhen a safety limit condition is exceeded for 3consecutive cycles the control board enters the limit intomemory and the ice machine continues to run. Use thefollowing procedures to determine if the control boardcontains a safety limit indication.1. Move the toggle switch to OFF.2. Move the toggle switch back to ICE.3. Watch the harvest light. If a safety limit has beenrecorded, the harvest light will flash one or twotimes, corresponding to safety limit 1 or 2.When a safety limit condition is exceeded (6 consecutivecycles for Safety Limit #1 or 500 cycles for Safety Limit#2) the ice machine stops and the harvest light on thecontrol board continually flashes on and off. Use thefollowing procedures to determine which safety limit hasstopped the machine.1. Move the toggle switch to OFF.2. Move the toggle switch back to ICE.3. Watch the harvest light. It will flash one or two times,corresponding to safety limit 1 or 2 to indicate whichsafety limit stopped the ice machine.After safety limit indication, the ice machine will restartand run until a safety limit is exceeded again.Safety Limit IndicationControl Board with Black MicroprocessorWhen a safety limit condition is exceeded for 3consecutive cycles the ice machine stops and theharvest light on the control board continually flashes onand off. Use the following procedures to determinewhich safety limit has stopped the ice machine.1. Move the toggle switch to OFF.2. Move the toggle switch back to ICE.3. Watch the harvest light. It will flash one or two times,corresponding to safety limits 1 and 2, to indicatewhich safety limit stopped the ice machine.After safety limit indication, the ice machine will restartand run until a safety limit is exceeded again.Orange LabelPart No. 80-1100-3 7-13