Panasonic U-120ME2U9 Service Manual page 171

4. 2WAY Alarm Codes
3. 2WAY Alarm Codes
P03, P17 Alarm
Alarm code P03, P17
Alarm meaning P03 : 1st compressor discharge temperature too high.
P17 : 2nd compressor discharge temperature too high.
Alarm conditions 1st compressor : Pre-trip stops when the temperature exceeds 223°F (106°C).
2nd compressor : Pre-trip stops when the temperature exceeds 223°F (106°C).
* The alarm occurs when pre-trip stop occurs more than once. However the pre-trip counter is cleared
if the compressor operates continuously for a specified length of time (more than 2.5 minuites).
Probable cause (1) Malfunction of expansion valve (MOV4)
(2) Insufficient amount of refrigerant
(including trouble resulting from an insufficient initial charge and from gas leakage)
(3) Blocking of low-pressure parts caused by intrusion of foreign objects (moisture, scale, etc.)
(4) Malfunction of expansion valves (MOV1, MOV2)
(5) Refrigerant is accumulated into the stopped outdoor units.
(6) Compressor discharge sensor failure
(7) Outdoor Unit Control PCB failure
(8) Failure to open the service valve of the outdoor unit
(9) Electrical noise
Check (1) Malfunction of expansion valve (MOV4)
Trouble: Although the expansion valve (MOV4) opens (MOV4 does not indicate "0" on the monitoring
Check:
(2) Insufficient refrigerant
Trouble: Liquid effectiveness is poor.
Check:
(3) Refrigerant is accumulated into the stopped outdoor units.
Trouble: System is OK when all outdoor units are operating, however symptoms of insufficient gas
Check:
(4) Sensor failure
Check:
(5) Failure to open the service valve of the outdoor unit
Check open/closed status of the outdoor unit service valve.
(6) If the cause is still unknown after checking the above, there is possibility that electrical noise is the
cause of the trouble.
Correction (1) Replace the sensor.
(2) Replace the Outdoor Unit Control PCB.
(3) Correct the problem locations.
Example All of the probable causes
software), the discharge temperature of the said compressor does not decrease.
Check whether the MOV4 secondary side refrigerant tube is cold when the expansion valve
(MOV4) opens.
Check whether or not the superheating temperature is declining if the expansion valves
(MOV1, MOV2) are opened to 300 pulses or more (after checking for foreign object
intrusion).
•
occur when a certain outdoor unit is stopped.
• Condensation or frost is visible up to the top of the accumulator of the stopped outdoor unit.
• After an outdoor unit stops, there is the sound of refrigerant flowing into an outdoor unit
that was stopped for a long time.
• When an outdoor unit starts after being stopped for a long time, the start is accompanied
by much vibration.
• Check the following points limited to the stopped outdoor units (while the other outdoor
units are operating).
• Refrigerant leak on the expansion valves (MOV1, MOV2, MOV4)
• The expansion valve of the outdoor units stopped are all closed without any sound.
The sound of refrigerant flow can be heard when refrigerant leaks.
• Close the liquid service valve (normally "open") and check whether the sound of
refrigerant flow can be heard. When the sound stops, refrigerant leaks.
• If refrigerant leaks from the expansion valve (MOV4), the temperature of the secondary
refrigerant tube becomes lower than the outdoor temperature.
• Refrigerant leaks from the expansion valve (MOV1, MOV2).
• When the outdoor units stopped, there is no refrigerant flow normally. But once
refrigerant leaks, the sound of refrigerant flowing from the check valve can be heard.
• Close the liquid tube service valve (normally "open") and check whether the sound of
refrigerant flow from the check valve stops. When the sound stops, refrigerant leaks.
• This alarm is likely to occur when wiring is partially cut. (It is difficult to identify, even
when continuity is checked.) The detected discharge temperature is high.
• Replace the sensor with another discharge sensor and compare the temperature conditions.
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2WAY SYSTEM
2WAY VRF SYSTEM
Trouble Diagnosis
Trouble Diagnosis
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