Sequence Of Operation Ude080 - Manitowoc UDE065A Technician's Handbook

Sequence of Operation UDE080

Initial start-up or start-up after automatic shut-off
1. Pressure Equalization
Before the compressor starts the hot gas valve is energized
for 15 seconds to equalize pressures during the initial
refrigeration system start-up.
2. Refrigeration System Start-up
The compressor starts after the 15-second pressure
equalization, and remains on throughout the entire Freeze
and Harvest Sequences. The hot gas valve remains on for 5
seconds during initial compressor start-up and then shuts
off. At the same time the compressor starts, the condenser
fan motor (air-cooled models) is supplied with power
throughout the entire Freeze and Harvest Sequences. The
fan motor is wired through a fan cycle pressure control,
therefore it may cycle on and off. (The compressor and
condenser fan motor are wired through the relay. As a
result, any time the relay coil is energized, the compressor
and fan motor are supplied with power.)
3. Prechill
The compressor is on for 30 seconds prior to water flow to
prechill the evaporator.
4. Freeze
The water pump starts after the 30-second prechill. An
even flow of water is directed across the evaporator and
into each cube cell, where it freezes. When sufficient ice
has formed, the water flow (not the ice) contacts the
ice thickness probe. After approximately 7 seconds of
continual water contact, the Harvest Sequence is initiated.
The ice machine cannot initiate a Harvest Sequence until a
6-minute freeze time has been surpassed.
82 Part Number 000014797 Rev02 05/18