Service manual

Section 7 Refrigeration System
Part No. 80-1206-3 7-27
Pressure Control Specifications and
Diagnostics
WATER REGULATING VALVE
Function
The water regulating valve maintains the freeze cycle
discharge pressure. The valve setting for the CVD1476
condensing unit is 240 psig.
Check Procedure
1. Determine if the head pressure is high or low (refer
to Operational Pressure Chart”)
2. Verify the condenser water meets specifications
(refer to section 2 for specifications).
3. Adjust valve to increase or decrease discharge
pressure (if discharge pressure remains high refer to
“Headmaster Control Valve Diagnostics” before
replacing valve).
4. Determine the temperature of the liquid line entering
the receiver by feeling it. This line is normally warm;
“body temperature”.
5. Using the information gathered, refer to the chart
below.
FAN CYCLE CONTROL
CVD0875/CVD1075/CVD1285/CVD1475/
CVD1875/CVD2075
Function
Energizes and de-energizes the condenser fan motor.
The condenser fan motor typically will be on in the
freeze cycle and off in the harvest cycle. Cycling allows
the discharge gas to bypass the condenser (through the
headmaster valve) and enter the receiver. This will
maintain the receiver temperature as the liquid
refrigerant is boiled off in the harvest cycle.
The fan cycle control closes on an increase, and opens
on a decrease in discharge pressure.
Specifications
Check Procedure
1. Verify fan motor windings are not open or grounded,
and fan spins freely.
2. Connect manifold gauges to ice machine.
3. Hook voltmeter in parallel across the fan cycle
control, leaving wires attached.
4. Refer to chart below.
Problem Cause
Freeze Cycle
Valve not maintaining
discharge pressure
Valve incorrectly set, dirty or
defective.
Adjust valve to 240 psig,
clean or replace valve.
Discharge pressure extremely
high; Liquid line entering
receiver feels hot
Water regulating valve
incorrectly set or not opening.
Verify Head Pressure Control
Valve operation before
changing water regulating
valve.
Discharge pressure low,
Liquid line entering receiver
feels warm to hot
Ice machine low on charge.
Refer to “Refrigerant Charge
Verification”
Model Cut-In (Close) Cut-Out (Open)
CVD0875
CVD1075
CVD1285
CVD1475
CVD1875
250 psig ±5 200 psig ±5
CVD2075 250 psig ±5
275 psig ±5
200 psig ±5*
225 psig ±5*
*The CVD2075 has two fans and two fan cycling controls.
FCC SETPOINT: Reading Should Be: Fan Should Be:
above cut-in 0 volts running
below cut-out line voltage off