Panasonic U-8ME2E8 Service Manual & Test Run Service Manual page 172

3. 2WAY Alarm Codes
H21, H31 Alarm
Alarm code
Alarm meaning
Alarm conditions
Probable cause
Check
6
Correction
Example
Notes
H21, H31
H21 : Compressor 2 HIC trouble alarm
H31 : Compressor 1 HIC trouble alarm
This alarm occurs when the microcomputer identifies a trouble signal (indicating abnormal HIC
temperature or other trouble) from the HIC.
The HIC judges the current and temperature, and outputs the trouble signal. In general this
indicates trouble with the HIC itself.
(1) Power supply voltage malfunction
(2) Overcurrent HIC caused the HIC failure by abnormal temperature.
(1) Check the power supply and voltage. Check whether the voltage between each of the phases
is correct while the compressor is running.
（It is necessary to check the compressor while running because the voltage may decrease
when the compressor starts running.）
(2) Right or wrong decision of HIC PCB IPM
Carry out the judgement of HIC PCB IPM in the following method. If the result of
measurement shows the resistance value of the fault diagnosis, replace the HIC PCB.
■ Right or wrong decision of HIC PCB IPM
Measure the resistance value between the + side (P) and - side (NW) of the HIC PCB.
・ Use the analogue tester when measuring. Measure by the k -range.
・ Measure as single item PCB. (Remove the wires, etc.)
・ Measure as terminal part. (See the figure.)
Resistance value of fault diagnosis: Less than 1k
(3) Radiation failure of HIC. Check the follows.
・ Confirm that radiation surface of the rear HIC PCB and the radiation plate of the electrical
component box contact properly. Putty of thermal conductivity is proplery adhered.
・ No screws loose.
・ Cooling air flows properly through the rear radiation plate of the electrical component box
(fin part). (Clogged in the airflow, etc.)
HIC PCB
HIC
-(NW)
HIC
+(P)
(1) Correct the power supply voltage.
(2) HIC failure and PCB replacement
(3) Improve the HIC radiation failure. Additional description is required in the manual.
—
Disconnect the power supply.
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2WAY SYSTEM
Trouble Diagnosis