Thermo King 914970, Manual

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123
Refrigeration Service Operations
NOTE: It is generally good practice to replace
the filter-drier whenever the high side is opened
or when the low side is opened for an extended
period of time.
Commissioning Unit
The following procedure should be followed after
any of these conditions:
• The compressor has been replaced
• There has been a large oil loss in the system
• There has been a complete clean up or flush of
the refrigeration system.
1. Set the thermostat to the highest setpoint.
2. Run the unit for ten minutes to allow for
wetting of the system.
3. Set the thermostat for Cool (remove jumpers if
installed in the previous step).
Low Side Pump Down
NOTE: Operate the unit in COOL for 2 to 5
minutes before performing the low side pump
down.
1. Unplug the hot gas bypass solenoid.
2. Install a gauge manifold to the suction service
valve and the discharge service port.
3. Operate the unit in low speed cool.
4. Close the receiver tank outlet valve and allow
the low side to pump down to 0 to 5 in. Hg
vacuum (0 to -17 kPa).
5. Turn the unit Off.
6. Prepare to perform service on the low side by
equalizing the high side and low side
pressures through the gauge manifold.
7. Equalize low side pressure to 1 to 2 psig (7 to
14 kPa).
NOTE: Repeat the pump down procedure if
the pressures equalize above 20 psig
(138 kPa). If acceptable low pressures
cannot be achieved after the third pump
down, the refrigerant must be recovered to
perform service on the low side.
NOTE: Valve stem MUST be back seated
during normal unit operation.
8. Plug in the hot gas bypass solenoid.
9. Open the receiver tank return outlet valve,
remove the gauges and return the unit to
normal operation.
Accumulator
Removal
1. Remove refrigerant using approved methods.
2. Unsolder the inlet and outlet refrigerant
suction lines from the accumulator tank.
3. Unbolt and remove the accumulator from the
unit.
Installation
1. Place the accumulator in the unit and tighten
the mounting bolts.
2. Solder the inlet and outlet suction lines to the
accumulator tank.
3. Pressurize the low side and test for refrigerant
leaks. If no leaks are found, evacuate unit.
4. Charge the system with refrigerant. Check
refrigerant charge and compressor oil and add
as required.