Refrigeration Service Operations
150
4. Recharge the unit with the proper refrigerant
and check the compressor oil.
Discharge Pressure Transducer
Removal
1. Recover the refrigerant charge.
2. Disconnect the wires and remove the
discharge pressure transducer.
Installation
1. Apply a refrigerant Loctite to the threads of
the discharge pressure transducer.
2. Install and tighten the discharge pressure
transducer and reconnect the wires.
3. Pressurize the refrigeration system and test for
leaks. If no leaks are found, evacuate the
system.
4. Recharge the unit with the proper refrigerant
and check the compressor oil.
Suction Pressure Transducer
Removal
1. Pump down the low side and equalize pressure
to slightly positive.
2. Disconnect the wires and remove the suction
pressure transducer.
Installation
3. Apply a refrigerant Loctite to the threads of
the suction pressure transducer.
4. Install and tighten the suction pressure
transducer and reconnect the wires.
5. Pressurize the low side and check for leaks. If
no leaks are found, evacuate the low side.
6. Open the refrigeration valves and place the
unit in operation.
Electronic Throttling Valve
(ETV)
Removal
1. Pump down the low side and equalize the
pressure to slightly positive.
2. The ETV must be open to remove the stepper
motor and piston assembly. Open the ETV by
placing the unit in the Evacuation Mode/Test,
and then disconnecting the ETV harness from
the four-pin connector on the main/unified
harness before turning the unit off. The
microprocessor closes the ETV when the unit
is turned off. Refer to the appropriate
Microprocessor Diagnostic Manual for
information about the Evacuation Mode/Test.
3. Unscrew the large nut that attaches the stepper
motor and piston assembly to the valve body.
The torque on the nut is approximately 118
ft-lb (160 N•m). Hold the valve body with
backup wrench to prevent damage to the
refrigeration tubing.
CAUTION: Unscrew the large nut. Do not
unscrew the small hex on the stepper
motor.
WARNING: If the ETV is stuck in the
closed position, much of the refrigerant
charge may be trapped in the evaporator
and accumulator. If you hear refrigerant
begin to flow through the valve when the
stepper motor and piston assembly are
loosened, unscrew the stepper motor and
piston assembly no more than four turns
and check the suction (low side) pressure
on the gauge manifold. If the suction
pressure has increased from the pressure
to which it was equalized after the low side
pump down, refrigerant is trapped and
must be recovered. Screw the stepper
motor and piston assembly back into the
valve body. Attach a refrigerant recovery
device to the service port on the receiver
tank outlet valve. Midseat the receiver tank
outlet valve, and recover the refrigerant
charge. The stepper motor and piston
assembly may then be removed.
