Compressor Start Windings; Thermal Overload Protector; Head Pressure Control - Cornelius I-SERIES Training Manual

Compressor Start Windings

Check the compressor start windings.
1. With the power disconnected use an ohm meter to
check each pair of terminals. There should NOT
be an open circuit.
2. Take an amp reading from the red wire during
defrost mode. The amps should match those on the
name plate. Low amps indicate low refrigerant.
3. Check the voltage at the compressor terminals while the compressor is trying to
start. The voltage should be at least 90% of line voltage.
4. Refer to the I Series Ice Cube Machine Service Manual & Maintenance Guide for
additional compressor starting tests.

Thermal Overload Protector

Check the Thermal Overload Protector by discon-
necting one of the wires and checking for continuity
(make sure the compressor has cooled).

Head Pressure Control

The Cornelius "I" series
remote systems use an Alco
Head Pressure Control, nor-
mally referred to as a head-
master. This control is
mounted in the remote con-
denser with a fan cycling
control switch. Using both
these controls gives the sys-
tem positive operation under a wide range of condensing temperatures.
The normal flow pattern through the headmaster is from the condenser port to the
receiver port. When this flow pattern is unable to maintain a receiver outlet pressure
equal to or above the dome pressure setting of the valve, the dome pressure will force
the valve port to change, closing the condenser port and opening the bypass port
from the compressor discharge line. This allows the high pressure vapor from the
discharge port to "buck" the receiver pressure back up. With the condenser port
closed, the refrigerant is backed up in the condenser, basically reducing the con-
denser size, assisting in maintaining the discharge port flow, and increasing the head
pressure.
© 2001, IMI Cornelius Inc.
I-Series Ice Machine Training Manual
Terminals
Red wire
Thermal overload protector
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