Panasonic U-8MF2E8 Service Manual page 140

4. 3WAY Alarm Codes
H06 Alarm
Alarm code
Alarm meaning
Alarm conditions
Probable cause
Check
Correction
5
Example
H06
Abnormal decrease of low-pressure
• Low-pressure sensor detects lower than 0.06MPa continuously for 2 minutes or lower than 0.02MPa
for just a moment.
(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
(5) Refrigerant is accumulated into the stopped outdoor units.
(1) Low-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 low-pressure outlet and check for changes in the value dispalyed 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.
(5) Refrigerant is accumulated in a state of stop mode of the outdoor units.
Leakage of expansion valve and solenoid valve in the outdoor unit in stop mode, etc.
(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.
• Dissolve insufficiency of refrigerant gas
(Correction of gas leakage area, additional refrigerant, etc.)
When charging additionally because of refrigerant insufficiency, add each 500g of refrigerant
little by little.
• 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.
indicates a short circuit or other trouble.
(low-pressure sensor pin 1-3)
indicates an open circuit or other trouble.
5 - 18
3WAY SYSTEM
Trouble Diagnosis
is normal.