Johnson Controls HVWHP072B32S - Page 77

SM-18006
3-57
TROUBLESHOOTING
l
 TheRUNindicator(red)ashes.
l
The indoor unit number (refrigerant cycle number - address number), the alarm code, the model code
1
,
the model name
1
and the number of connected indoor units are displayed on the LCD. The water source
unit number and the alarm code are displayed on the 7-segment display of the water source unit PCB.
Note 1: Except for some models.
If the discharge gas superheat is less than 18
o
F (10
o
C) at the top of the compressor continues for
30 minutes, retry operation is performed. However, when the alarm occurs twice within 120 minutes, this
alarm code is displayed.
W.S. PCB: Water Source Unit PCB (PCB1)
I.U. PCB: Indoor Unit PCB
Thermo-ON:
The water source unit and some indoor units are running.
Thermo-OFF:
The water source unit and some indoor units stay on, but don’t run.
Alarm
Code
Decrease in Discharge Gas Superheat
Model
Thermistor
Td1
(THM8)
Td2
(THM9)
(H,Y)VWH(P,R)072-120B(3,4)2S ▬
(H,Y)VWH(P,R)144-216B(3,4)2S
MV1 MVB
CN10 CN12
2: W.S. PCB Connector No. is shown below.
1: Refer to "Characteristics of Thermistor" of "Alarm Code 23".
Is the thermistor on
top of compressor
normal?
1
Is superheat value
under 18
o
F (10
o
C)?
Yes
Check the high-pressure,
compressor discharge
gas temperature and
calculate superheat value
by W.S. PCB.
Remove sudden
fluctuation of load
like short path by
discharge air from the
water source unit, or
the cause of frequent
thermo-ON/OFF.
Faulty Thermistor
No
No
Is the thermistor
installed correctly
on the compressor?
Yes
Install it correctly.
No
Was it at cooling or
heating mode when
the alarm occurred?
Do the refrigerant
piping and communication
cable match within the same
refrigerant system group?
Is refrigerant
correctly charged?
Is gas leaking?
Yes
Yes
Yes
Yes
Yes
Is superheat value
under 18
o
F (10
o
C)?
Cooling
Check the high-pressure,
compressor discharge
gas temperature and
calculate superheat value
by W.S. PCB.
Heating Operation
Cooling Operation
Heating
No
Pl
ug t
h
e connectors
2
of W.
S
. P
C
B
p
roper
l
y.
No
Charge correct
refrigerant volume.
No
Perform self-checking
by W.S. PCB.
Check the expansion
valve.
No
No
Match the refrigerant
piping and communication
cable with the same
refrigerant system group.
Repair leaks of gas.
Correctly charge
refrigerant.
No
Is the opening of the
water source unit heat
exchanger's expansion
valve under 8%?
Are the connectors
2
of W.S. PCB of the
water source unit heat
exchanger's electronic
expansion valve
connected properly?
Yes
Yes