Panasonic U-72MF2U9 Service Manual page 178

3. 3WAY Alarm Codes
H06 Alarm
Alarm code
Alarm meaning
Alarm conditions
Probable cause
Check
1
2
3
Correction
4
5
Example
6
7
8
9
H06
Low pressure is too low.
• 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
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 95k - 105k , 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.
(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 17.6oz (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.
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3WAY VRF SYSTEM
Trouble Diagnosis