Panasonic U-8ME1E81 Service Manual page 158

4. 2WAY Alarm Codes 4. 3WAY Alarm Codes
F16 Alarm
Alarm code
Alarm meaning
Alarm conditions
Probable cause
Check
Correction
6
Example
F16
High-pressure sensor malfunction
• High-pressure sensor disconnected or open circuit
• High-pressure sensor detected over 3.6MPa continuously for 30 minutes while outdoor units stopped.
• High-pressure sensor detected over 3.6MPa while outdoor units were operating.
(In some cases, start and stop may sometimes repeat due to pre-trip mode.)
(1) High-pressure sensor failure
(2) Failure to connect the connector to the outdoor unit PCB
(3) Failure to open the service valve of the outdoor unit
(4) Clogged refrigerant circuit
(5) Refrigerant over-charging
(6) Outdoor unit PCB failure
(1) High-pressure sensor failure
• Check the sensor resistance value. (Use a tester and measure the resistance between sensor No. 1
and No. 3)
Resistance of less than 95k
Resistance of 95k - 105k
Resistance of more than 105k
• Connect a gauge to the high-pressure outlet and check for changes in the value displayed by the
monitoring software, and for large deviation of the gauge pressure.
• During heating, check whether the temperature is lower than the highest indoor-unit E1 temperature.
*The pressure detected by the high-pressure sensor is the highest pressure in the system.
Therefore during heating the converted saturation temperature will never be lower than any
indoor-unit E1 temperature. During cooling this temperature will never be lower than the outdoor
unit liquid temperature.
(2) Failure to connect the connector to the outdoor unit PCB
Check the connector connected to the outdoor unit PCB
(3) Failure to open the service valve
Check the open/closed status of the service valve.
(4) Check for clogging of the refrigerant circuit.
When clogging or over-charging occurs, refrigerant is likely to accumulate in the outdoor unit (cooling)
and indoor unit (heating). Sudden rise in pressure at start may sometimes occur.
(6) Outdoor unit PCB failure
• The check items are the same as for a high-pressure sensor malfunction.
A normal PCB is needed to determine whether the problem is a PCB failure or a pressure sensor
malfunction. If an abnormality was found at the check items for a high-pressure sensor malfunction,
first try replacing the PCB and check again.
Trouble is corrected: Outdoor unit PCB failure
Trouble is not corrected: High-pressure sensor malfunction
(1) Replacement of high-pressure sensor
When replacing a high-pressure sensor, carry out after refrigerant recovering of outdoor unit.
(2) Replacing the PCB
(3) Correct malfunction of refrigerant cycle.
• Open valve of outdoor unit.
• Correct clogging.
• In the case of refrigerant over-charging, recover appropriate amount of refrigerant.
Standards of over-charging
Install the pressure gauge at the high-pressure removal port of outdoor units and check for it.
During cooling: Not available in case of low outdoor temperature or adjusting the outdoor fan.
While both the compressors 1 and 2 are operating under 12-step or 13-step in the
fan mode, high-pressure's saturation temperature indicates the outdoor temperature
+ around 15°C.
If the temperature is 5°C higher than the said temperature, over-charging might be
expected.
During heating: There is an indoor unit where refrigerant flow is poor (E1 temperature and discharge
temperature are low), and the mechanical valve of that unit is opened to 300 pulses
or more, and the E1 temperature is close to room temperature. However be aware
that this kind of data results often when there is a height difference between indoor
units. Reducing the amount of refrigerant will improve the refrigerant flow, however
reducing it too much will increase the likelihood of alarms related to low oil level
(scroll-side), the low pressure SW, and discharge temperature. Use caution.
Malfunction had occurred when the liquid, suction and discharge tubes were clogged together.
indicates a short circuit or other trouble.
(high pressure sensor pin 1-3)
indicates an open circuit or other trouble.
(5) Check for refrigerant over-charging.
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3WAY SYSTEM
2WAY SYSTEM
Trouble Diagnosis
Trouble Diagnosis
is normal.