TABLE 6-1 Partial Pumpdown Time

NOTE: The PLC uses the cylinder ice pressure switch (FPS2) as a partial pumpdown safety. Do not remove this pressure switch from the machine.

Initiated by the following:

1. At the end of a harvest cycle with the bin thermostat satisfied.

2. At the end of a harvest cycle with the “Ice” switch in the “Off” position.

Total Pumpdown Mode. The function of the total pumpdown mode is to transfer all the liquid

refrigerant from the freezer (evaporator) into the receiver. Total pumpdown is initiated as the first phase of and prior to entering the “Clean” mode.

Its main purpose is to clear the freezer of liquid refrigerant and prevent possible refrigerant migration to the compressor while running the “Clean” cycle. It can also be used to check the units total refrigerant charge, isolate the refrigerant in the receiver while making repairs, or prepare the machine for disconnecting and moving.

Initiated by the following:

1. Set the “Selector” switch to the “Cyl” position (dual ice type machines only).

2. Turn the “Ice” switch to the “Off” position (allow the machine to harvest if it is operating). 3. Push the “Clean” button into the “On” position. At this time the compressor and water pump will

run, the “A” (liquid feed) solenoid valve will close and the freezer will begin to pumpdown. As the suction pressure decreases, the freezer pressure switch will initiate a harvest cycle to clear the partially formed ice cylinders from the freezer. This harvest cycle will end after one minute and the total pumpdown will resume continuing until the compressor cycles off by the low pressure switch. At this time, only the water pump will be running. The “Clean” button must then be pushed to the “Off” position and the machine will be in the standby mode.

HEC-Series Service Manual ELECTRICAL CONTROLS & THEIR FUNCTIONS

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1. Set the “Ice Selector” switch to the position desired. 2. See that the “Clean” switch is in the “Off” position. 3. Push the “Ice” button to the “On” position.

4. Push the “Start” button. (Make sure the compressor crankcase is warm and there is no liquid refrigerant in with the oil before pushing the “Start” button.)

At this time the “A” (liquid feed) solenoid valve will open for two minutes, allowing the freezer pressure to raise to the cut-in setting of the low pressure switch. Then the machine will start in a freeze cycle.

Clean Mode. The “Clean” mode is considered to be a maintenance or servicing function of the

machine. It should only be initiated when the freezer is clear of ice. The first phase of the “Clean” mode is a total pumpdown.

! CAUTION !

Do not attempt to bypass the total pumpdown phase of the “Clean” mode. If a clean cycle is performed without first completing a total pumpdown, the warm water being circulated through the freezer tubes can force refrigerant to migrate to the suction accumulator and compressor. This could create an unfavorable condition and possible cause damage to the compressor when returning to the freeze mode.

! CAUTION !

After the total pumpdown and pushing the “Start” button, the water pump can be started and stopped by simply pushing the “Clean” button on and off. (Note: If the freezer and compressor suction pressure have come up enough to open the freezer pressure switch FPS2 and close low pressure safety switch 4PS, the compressor will come and on and pump down the freezer again.) Ice machine cleaning solution can be circulated though the tubes to accomplish the cleaning procedure. If the water pump is left to run in the clean mode. The clean mode can be resumed by pushing the “Start” button.

At the termination of the clean mode, the machine can be returned to ice making mode by pushing the “Clean” button to the “Off” position; the “Ice” button to the “On” position; and the “Start” button. See “Maintenance--Ice Making”, Section 7, for complete cleaning procedure.

Troubleshoot Mode. If the machine has stopped due to a “fault” during normal operation, a

troubleshoot mode can be used to identify this “fault”. This mode can be entered from a start-up or standby mode.

To enter the troubleshoot mode, the SVI (service indicator) switch located inside the control panel (FIGURE 6-1) must be opened. This will disable the machine and its components.

Initiated by the following: 1. Open the SVI switch.

2. Set the “Clean” button to the “On” position. 3. Set the “Ice” button to the “On” position.

4. Push both the “Harvest” and “Start” buttons simultaneously.

At this point, the machine “fault” can be identified and necessary corrections or adjustments can be made for returning the machine to good working order. A “fault” will be identified by illumination of specific numbered PLC output indicator lights on the PLC. See “Fault Identity”, TABLE 6-2.

To exit the troubleshoot mode, follow this sequence: 1. Set the “Clean” button to the “Off” position. 2. Set the “Ice” button to the “Off” position. 3. Close the SVI switch.

4. This will return the machine to the “Start-Up” mode.

Output Light Fault # Fault Description

ll¬l¬l #10 High or low pressure cutout during freeze cycle ll¬l¬¬ #11 High or low pressure cutout during harvest cycle ll¬¬ll #12 High or low pressure cutout during partial pumpdown ll¬¬l¬ #13 High or low pressure cutout during total pumpdown ll¬¬¬l #14 Short Cycle Fault:

Three Harvests Within A Specified Time As Noted: HEC-10 --- 10 Minutes

HEC-20 --- 10 Minutes HEC-30 --- 5 Minutes HEC-40 --- 5 Minutes ll¬¬¬¬ #15 Long Freeze Cycle Fault:

One Freeze Cycle Longer Than A Specified Time As Noted: HEC-10 --- 120 Minutes

HEC-20 --- 120 Minutes HEC-30 --- 80 Minutes HEC-40 --- 60 Minutes l¬llll #16 Power failure/compressor O/L Note: ¬ indicates light is “On”

TABLE 6-2