37
Installation and Maintenance
Service Manual
14/18K:
24/28K:
43 Communication failure with Unit A
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Ƽ
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44 Communication failure with Unit B
Ƽ
Ƽ
●
●
45 Communication failure with Unit C
○
○
Ƽ
●
46 Communication failure with Unit D
●
○
Ƽ
●
47 Unit A freeze protection
Ƽ
○
Ƽ
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48 Unit B freeze protection
○
●
Ƽ
●
49 Unit C freeze protection
●
●
Ƽ
●
50 Unit D freeze protection
Ƽ
●
Ƽ
●
51 Unit A
overheating prevention protection
○
Ƽ
Ƽ
●
52 Unit B
overheating prevention protection
●
Ƽ
Ƽ
●
53 Unit C
overheating prevention protection
Ƽ
Ƽ
Ƽ
●
54 Unit D
overheating prevention protection
○
○
○
Ƽ
55 Unit A communication wire misconnection or expansion valve malfunction
●
○
○
Ƽ
56 Unit B communication wire misconnection or expansion valve malfunction
Ƽ
○
○
Ƽ
57 Unit C communication wire misconnection or expansion valve malfunction
○
●
○
Ƽ
58 Unit D communication wire misconnection or expansion valve malfunction
●
●
○
Ƽ
Note: discharge the position in below pictures with discharge resistance after open the top cover and
check if the voltage is below 20V with universal meter, then begin to check.
1 IPM protection malfunction:
Main checking point:
● If the input voltage of the unit is within normal range?
● If the connection wire of compressor is connected well? Is it loose? If the connection sequence is correct?
● If the resistance of compressor coil is normal? If the isolation of compressor coil with copper pipe is good?
● If the unit is overloaded? If the heat radiation of the unit is good?
● If the refrigerant charge is suitable?
Flow chart:
14/18K:
24/28K:
43 Communication failure with Unit A
●
Ƽ
●
●
44 Communication failure with Unit B
Ƽ
Ƽ
●
●
45 Communication failure with Unit C
○
○
Ƽ
●
46 Communication failure with Unit D
●
○
Ƽ
●
47 Unit A freeze protection
Ƽ
○
Ƽ
●
48 Unit B freeze protection
○
●
Ƽ
●
49 Unit C freeze protection
●
●
Ƽ
●
50 Unit D freeze protection
Ƽ
●
Ƽ
●
51 Unit A
overheating prevention protection
○
Ƽ
Ƽ
●
52 Unit B
overheating prevention protection
●
Ƽ
Ƽ
●
53 Unit C
overheating prevention protection
Ƽ
Ƽ
Ƽ
●
54 Unit D
overheating prevention protection
○
○
○
Ƽ
55 Unit A communication wire misconnection or expansion valve malfunction
●
○
○
Ƽ
56 Unit B communication wire misconnection or expansion valve malfunction
Ƽ
○
○
Ƽ
57 Unit C communication wire misconnection or expansion valve malfunction
○
●
○
Ƽ
58 Unit D communication wire misconnection or expansion valve malfunction
●
●
○
Ƽ
Note: discharge the position in below pictures with discharge resistance after open the top cover and
check if the voltage is below 20V with universal meter, then begin to check.
1 IPM protection malfunction:
Main checking point:
● If the input voltage of the unit is within normal range?
● If the connection wire of compressor is connected well? Is it loose? If the connection sequence is correct?
● If the resistance of compressor coil is normal? If the isolation of compressor coil with copper pipe is good?
● If the unit is overloaded? If the heat radiation of the unit is good?
● If the refrigerant charge is suitable?
Flow chart:
Energize the unit
If the above cases are existed?
Test the isolation impedance
between the three phases of the
compressor and thecopper pipe
Malfunction is eliminated
End
If the wire of compressor is connected
well and correctly?
Correct according to the service
manual and then energize the
unit to operate
Test the resistance between
the three phases
Reconnect the wire of the
compressor according to the
correct wiring method
If the resistance is normal?
If the resistance is above 500M ?
Replace the
compressor
Replace the outdoor
mainboard
Please check:
1. if the indoor and outdoor heat exchanges are
dirty, if there is obstacle to affect the radiation;
2. if the indoor and outdoor fans are running
normally;
3. if the pressure of the system is too high;
4. if the refrigerant is too much which causes
the high level of pressure;
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
