Thermo King 914 724, Manual

Page: 67 / 111

Refrigeration Service Operations (Rev. 1/99)
57
Testing the Liquid Injection Solenoid
Valve and Metering Orifice
1. Disconnect the LIS wire from the liquid injection sole-
noid.
2. Install a gauge manifold set on the engine-driven com-
pressor.
3. Set the thermostat on the lowest setting.
4. Start the truck and run the unit on the engine-driven
compressor until the suction pressure stabilizes.
5. Place a jumper wire between CH and the LIS terminal
on the liquid injection solenoid.
6. With the jumper wire in place the suction pressure
should rise.
7. With the jumper wire removed the suction pressure
should return to the stabilized pressure in step 4.
8. If the suction pressure does not change, check the CLU
wire for voltage, the liquid injection solenoid valve, or
the metering orifice.
9. Shut off the unit and the truck, remove the gauge mani-
fold set and replace the LIS wire.
HIGH PRESSURE CUTOUT AND
CONDENSER FAN SWITCHES
Removal
1. Remove the refrigerant charge.
2. Disconnect the wires and remove the switch.
Installation
1. Apply a refrigerant locktite to the threads of the switch.
2. Install and tighten the switch and reconnect the wires.
3. Pressurize the refrigeration system and test for leaks.
4. If no leaks are found, charge the system.
LOW PRESSURE CUTOUT SWITCH
Removal
1. Pump down the low side and stop the unit.
2. Disconnect the wires and remove the switch.
Installation
1. Apply a refrigerant locktite to the threads of the switch.
2. Install and tighten the switch and reconnect the wires.
3. Pressurize the refrigeration system and test for leaks.
4. If no leaks are found, evacuate the low side.
5. Open the receiver tank outlet valve, start the unit and
check the refrigerant charge.
SUCTION PRESSURE REGULATOR
VALVE
Removal
1. Pump down the low side and equalize the pressure to
slightly positive.
2. Release the remaining pressure and unsolder the suc-
tion pressure regulator valve from the suction tubes.
Installation
1. Clean the tubes for soldering.
2. Place the valve in position and solder the connections.
3. Pressurize the low side and check for leaks.
4. If no leaks are found, evacuate the low side.
5. Open the refrigeration valves, and place the unit in
operation. Check refrigerant charge and add refrigerant
as required.