Thermo King CRR-40 119, Руководство пользователя

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Refrigeration Maintenance and Service Operations
136
5. Front seat the suction service valve and pump
down the system to 21 to 35 kPa, 0.21 to 0.35
bar, 3 to 5 psig.
6. Back seat the suction service valve.
7. Remove the hoses from the discharge service
valve.
8. Install a gauge manifold set.
• If the unit is fully charged, perform a
functional check out.
• If the unit has a partial charge, complete
the charging process as described below.
Final Charging Procedure for Partially
Charged Units
1. Connect the gauge manifold to the suction line
and discharge line service ports. Be sure to
purge the air from the lines (see “Gauge
Manifold Set Attachment and Purging” in the
Refrigeration Maintenance chapter of this
manual).
2. Back seat and crack the discharge service
valve.
3. Connect a refrigerant tank to the gauge
manifold service line.
4. Set the refrigerant tank for liquid charging.
Open the refrigerant tank hand valve.
5. Start and operate the unit in the COOL mode.
6. Read the suction pressure and slowly open the
gauge manifold low pressure hand valve to
permit suction pressure to increase
approximately 170 kPa, 1.7 bar, 25 psig. This
will meter liquid refrigerant slowly into the
low side.
7. Add refrigerant until the receiver tank balls
float in the top sight glass.
8. Close the hand valve on the refrigerant tank.
9. Operate the unit on COOL for 10 minutes and
recheck refrigerant charge.
10. Remove the gauge manifold set.
11. Cap all service ports and valve stems.
Evaporator Pressure Regulator
(KVQ) Valve
The evaporator pressure regulator valve is used to
control the flow of refrigerant to the compressor
when the unit is operating in the Power Limit and
Modulation Cool modes. As the supply air
temperature approaches setpoint, the controller
sends a voltage pulse to a heater in the valve. The
heater warms a pressure reservoir in the valve
actuator. As the pressure in the fluid reservoir
increases, a pressure pin overcomes the spring
tension in the bellows, closing the valve plate a
precise amount. This throttles the suction gas
returning to the compressor and reduces cooling
capacity. As the frequency of the voltage pulse is
increased, the pressure pin closes the valve plate
an additional amount. Due to valve design, the
flow of refrigerant gas exerts no opening or
closing forces on the valve plate, allowing very
precise operation.
NOTE: If electrical circuit to heating element
fails, the valve moves to the full open position.
Service of the evaporator pressure regulator valve
includes replacement of the actuator assembly or
replacement of the valve body.
Tools Required:
• Digital Multimeter (P/N 204-615)
• Actuator Assembly
• Adjustable Wrench
• Torque Wrench
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.
CAUTION: If the controller temperature
setpoint was lowered to force COOL
operation, be sure to return the controller
to the setpoint indicated on the shipping
manifest.