Panasonic U-4LE2E5 Service Manual & Test Run Service Manual page 141

3. Mini VRF Alarm Codes
4. 3WAY Alarm Codes
H05 Alarm
Alarm code H05
Alarm meaning Compressor discharge temperature sensor is disconnected, shorted or misplaced. (DISCH)
Alarm conditions • This alarm occurs when the discharge sensor temperature detector is not inserted into the tube's
sensor holder, or when the sensor itself has suffered some kind of malfunction other than a cut
wire.
• When outdoor air temperature is -10°C or higher:
Alarm occurs if the temperature detected by the discharge sensor has changed by less than
2°C when the compressor has operated for 10 minutes immediately after start.
• When outdoor air temperature is below -10°C:
Alarm occurs if the temperature detected by the discharge sensor has changed by less than
2°C when the compressor has operated for 30 minutes immediately after start.
Probable cause (1) Discharge sensor temperature detector is not inserted into the tube's sensor holder.
(2) Discharge sensor itself has suffered some kind of malfunction other than a cut wire.
Check (1) Check that the discharge temperature sensor is inserted into the sensor holder.
(2) Check that sufficient heat-conducting putty is applied.
(3) Remove the discharge sensor from the sensor holder and expose the sensor to the outside
air for approximately 5 minutes. Check that the temperature detected by the sensor changes
to match the outside air temperature. (However the sensor cannot detect temperatures at or
below 0 °C.)
Correction (1) Install the sensor into the holder, and apply sufficient heat-conducting putty.
(2) If the sensor is malfunctioning, replace it.
—
Example
H06 Alarm
Alarm code H06
Alarm meaning Low pressure sensor value is too low.
Alarm conditions • Low-pressure sensor detects lower than 0.06MPa continuously for 2 minutes or lower than
0.02MPa for just a moment.
Probable cause (1) Low-pressure sensor failure
(2) Failure to open the service valve of the outdoor unit
(3) Clogged refrigerant circuit
(4) Insufficiency of refrigerant gas amount
Check (1) Low-pressure sensor failure
• Remove the socket of low-pressure sensor from the Outdoor Unit Control PCB and measure the
resistance of each wire (×3) and between the outdoor unit and earth.
If this resistance is more than 1MΩ, it indicates normal. If not, replace the sensor.
• Connect a gauge to the low-pressure outlet and check for changes in the value displayed by the
monitoring software, and for large deviation of the gauge pressure.
(2) Failure to open the service valve of the outdoor unit
Check the open/closed status of the service valve.
(3) Check for clogging of the refrigerant circuit.
When clogging in the refrigerant circuit occurs, refrigerant does not return to the compressor.
As a result, low-pressure may occasionally decrease abnormally.
Then check the following points:
Solenoid valve, expansion valve, fleezing caused by contaminated water inside the circuit, etc.
(4) Insufficiency of refrigerant gas
When insufficiency of refrigerant charge amount or of refrigerant amount in the system caused by
gas leakage occurs, low-pressure may occasionally decrease abnormally.
Correction
(1) Replacement of low-pressure sensor
When replacing a low-pressure sensor, carry out after refrigerant recovering of outdoor unit.
(2) Correct malfunction of refrigerant cycle.
• Open valve of outdoor unit.
• Correct clogging.
(3) Dissolve insufficiency of refrigerant gas
• When refrigerant charge amount is insufficient, charge refrigerant little by little.
• When leak portion is detected and repaired, charge recovered amounts of refrigerant.
Example
• The alarm had occurred because of refrigerant insufficiency due to gas leak.
• The alarm had occurred when the liquid, suction and discharge tubes were clogged together.
6 - 13
Mini VRF SYSTEM 3WAY SYSTEM
Trouble Diagnosis Trouble Diagnosis
6