HEC-Series Service Manual
ELECTRICAL CONTROLS & THEIR FUNCTIONS
10/21/01
6-9
Partial Pumpdown Mode.
The partial pumpdown modes precedes the normal off or standby mode.
Its purpose is to transfer a portion of the liquid from the suction accumulator and freezer into the
receiver prior to shutdown of the machine (standby mode). This will discourage any migration of
liquid refrigerant to the compressor during the off or standby mode. It is also intended to help
prevent any liquid refrigerant slugging to the compressor when the machine restarts in a freeze mode.
When partial pumpdown is initiated, the “A” (liquid feed) solenoid valve is closed and the water
pump and compressor run for a set time. After this set time the compressor stops and the machine is
in the standby mode.
Model
HEC-10
HEC-20
HEC-30
HEC-40
Time
7 minutes
7 minutes
5 minutes
3 minutes
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.
To restart the machine after a total pumpdown:
Summary of Contents for HEC-10
Page 1: ...HEC SERVICE MANUAL ...
Page 95: ...HEC Series Service Manual SERVICE OPERATIONS 10 21 01 9 13 FIGURE 9 9 Cutter Water Tank Parts ...
Page 96: ...HEC Series Service Manual SERVICE OPERATIONS 10 21 01 9 14 FIGURE 9 10 Cutter Drive Parts ...
Page 97: ...HEC Series Service Manual SERVICE OPERATIONS 10 21 01 9 15 FIGURE 9 11 Cutter Parts ...
Page 106: ...HEC Series Service Manual MODEL NUMBER STRUCTURE 10 21 01 10 1 10 Model Number Structure ...
