6-14
Evaporator Pressure Regulator (KVQ Valve)
Refrigeration Maintenance and Service Operations
CRR-20 & CRR-40, September 1999
Heater Circuit Checkout Procedure
1.
Unplug the evaporator pressure regulator valve lead wire
harness.
2.
Using a FLUKE multimeter, test each lead (4) resistance
to ground. Low resistance indicates a short is present.
Repair or replace any damaged or exposed wires.
3.
Check the heater circuit and thermistor circuit resistance.
• A good heater circuit has a resistance of 20 ohms at 25 C
(78 F).
• A good thermistor circuit has a resistance of 20,000 ohms
at 25 C (78 F).
NOTE: The ohmmeter will display a slightly high-
er heater resistance if the valve was energized
just prior to testing the circuit resistance.
4.
To return the unit to service, plug the evaporator pressure
regulator valve lead connector into the unit wire harness.
Valve Actuator Replacement
If the evaporator pressure regulator valve fails to operate prop-
erly, remove the actuator cover and inspect the assembly for
rust or corrosion. Rust or corrosion can damage the actuator
or heater circuit, preventing the valve from operating properly.
1.
To replace actuator assembly, unplug the heater and ther-
mistor lead wire harnesses.
2.
Connect the unit’s main power cable to the main power
source and switch the refrigeration unit’s On/Off switch to
ON. Close the receiver tank outlet valve and pump down
the low side. Equalize suction pressure to to 21 kPa, 0.21
bar, 3 psig.
3.
Turn the unit On/Off switch to OFF. Then disconnect the
main power cable from the main power source again.
Close (front seat) the discharge service valve.
CAUTION: Any time the discharge valve is front
seated, disconnect the unit power source to pre-
vent accidental compressor start-up.
4.
Inspect the actuator terminals and note the wire connec-
tion sequence. Then disconnect wire leads.
5.
Unscrew the actuator assembly from the valve body.
6.
Immediately insert new actuator assembly in valve body.
7.
Thread new actuator into valve body until it is hand tight.
Then tighten to 45 N.m (33 ft-lb).
8.
Connect wire leads to actuator terminals in proper
sequence.
9.
Replace cover on actuator assembly.
KVQ Valve
1. Actuator Assembly
2. Threaded Connection
3. Valve Body
4. Inlet Tube
5. Valve Plate
6. Outlet Tube
7. Pressure Pin
8. Bellows Assembly
9. Pressure Reservoir
10. Heating Element
11. Terminal Connections
Summary of Contents for CRR-20
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