Manitowoc

Ice Thickness ProbeQM45/Q130/Q170/Q210/Q270How The Probe WorksManitowoc’s electronic sensing circuit does not rely onrefrigerant pressure, evaporator temperature, waterlevels or timers to produce consistent ice formation.As ice forms on the evaporator, water (not ice)contacts the ice thickness probe. After the watercompletes this circuit across the probe continuouslyfor 6-10 seconds, a harvest cycle is initiated.Freeze Time Lock-In FeatureThe ice machine control system incorporates a freezetime lock-in feature. This prevents the ice machinefrom short cycling in and out of harvest.The control board locks the ice machine in the freezecycle for six minutes. If water contacts the icethickness probe during these six minutes, the harvestlight will come on (to indicate that water is in contactwith the probe), but the ice machine will stay in thefreeze cycle. After the six minutes are up, a harvestcycle is initiated. This is important to remember whenperforming diagnostic procedures on the ice thicknesscontrol circuitry.To allow the service technician to initiate a harvestcycle without delay, this feature is not used on the firstcycle after moving the toggle switch OFF and back toON.Maximum Freeze TimeThe control system includes a built-in safety, which willautomatically cycle the ice machine into harvest after60 minutes in the freeze cycle.174 Part Number 80-01111-9 7/10