Electrical control system operation
The P425A/W, MCD425A/W_S and R425A/W wiring diagrams which follow illustrate the circuitry of Follett ice
machines used with ice dispensers. Both normal operation of the ice machine (Stages 1–6) and non-normal
diagnostic sequences showing torque-out (Stages 7–10) for use in troubleshooting ice machine problems are
When the ice machine is used with a dispenser it receives power from the main power supply. Disconnect the
power source before performing service. When performing electrical service, always use a meter to determine
whether or not the components being serviced are energized.
§High pressure cutout opens at 425 PSI and closes at 287 PSI (auto reset).
§The bin signal input to the control board in the 425A/W ice machine must only be initiated by contact closure. Do
not supply power. To run the ice machine in the workshop, use the bin signal jumper (P/N 01069095).
Note: The operation stage descriptions that follow are based on the unit containing the split-phase gear
Normal operation – Stage 1
Power is supplied to L1 of the control board, the POWER LED light begins ashing. The ice level bin thermostat in
the dispenser is closed and calling for ice, supplying contact closure to the control board. The LOW BIN LED will
be on. The control board will now go through the start-up sequence. The board checks the water sensors (located
in the reservoir) for continuity between the common probe (B) and the high probe (C). If continuity is not sensed,
the water ll valve (P21) is energized.
A B C D
Bin T-Stat Clean Switch
Drain Clog Sensor
1 2 3 4 5 6 7 8
Ice Dispense Input
MCD425A/W, R425A/W, MFD425A/W, P425A/W Ice Machines 15