Thermo King T-1080S, Maintenance Manual

Page: 144 / 191

Refrigeration Service Procedures
143
Discharge Pressure Transducer
Testing
The discharge pressure transducer is located on
the discharge line near the discharge strainer. It
supplies pressure information to the SR-3
Microprocessor Control System. Alarm Code 86
(Check Discharge Pressure Sensor) indicates a
possible problem with the discharge pressure
transducer. The pressure reading can be monitored
with a Mechanics/Premium HMI Control Panel by
pressing the
G
AUGES
key. Check the reading by
comparing it to the reading on a gauge attached to
the discharge service port. Refer to the
appropriate Microprocessor Diagnostic Manual
for more information about the testing and
operation of the discharge pressure transducer.
Discharge Pressure Transducer
Replacement
Removal
1. Recover the refrigerant charge.
2. Disconnect the wires and remove the
discharge pressure transducer from the
discharge tube.
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 system and test for leaks.
4. If no leaks are found, evacuate the system.
5. Recharge the unit with refrigerant and check
the compressor oil.
Discharge Strainer Test
If the discharge strainer is plugged or restricted,
the unit will stop very quickly after is starts to run
and will record Alarm Code 10 (High Discharge
Pressure). This can also be caused by a faulty
HPCO. It can be difficult to determine whether
the discharge strainer of the HPCO is causing this
problem. See the following procedure and
guidelines.
1. Connect a high pressure gauge to the
discharge service port to monitor the
discharge pressure.
2. Start the unit while watching the discharge
pressure.
• If the unit stops before the discharge
pressure rises at all, it is more likely to be
a plugged discharge strainer.
• If the discharge pressure rises before the
the unit stops, it is more likely to be a
faulty HPCO.
Because the refrigerant charge must be recovered
to replace the discharge strainer or the HPCO, it is
best to replace both the discharge strainer and the
HPCO if you are not sure which is causing the
problem.
NOTE: If the discharge strainer is plugged, it is
important to determine and repair the cause of
the debris.
Discharge Strainer
Replacement
Removal
1. Recover the refrigerant charge.
2. Remove the discharge strainer mounting
clamp.
3. Unsolder the refrigeration lines from the
discharge strainer and remove the discharge
strainer from the unit.
Installation
1. Clean the tubes for soldering.
2. Place the discharge strainer in position.
3. Solder the inlet and outlet connections.
4. Install the discharge strainer mounting clamp.
5. Pressurize the refrigeration system and test for
leaks.
6. If no leaks are found, replace the liquid line
drier then evacuate the system.
7. Recharge the unit with proper refrigerant and
check the compressor oil.