Johnson Controls YVAHP0721CW Series, Service Manual

Page: 216 / 416

3-52
SM-16007
TROUBLESHOOTING
O
7KH581LQGLFDWRUUHGÀDVKHV
O
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 indoor unit
number and the alarm code are displayed on the 7-segment display of the outdoor unit PCB.
*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 indicated.
Alarm
Code
Decrease in Discharge Gas Superheat
O.U. PCB: Outdoor Unit PCB
I.U. PCB:
Indoor Unit PCB
Thermo-ON:
The outdoor unit and some indoor units are running.
Thermo-OFF:
The outdoor unit and some indoor units stay on, but don’t run.
Model
Thermistor
Td1
(THM8)
Td2
(THM9)
(H,Y)VAHP072B(3,4)1CW
(H,Y)VAHP096B(3,4)1CW
*2): O.U. PCB Connector No. is shown below.
*1): Refer to "Characteristics of Thermistor" of "Alarm Code 23".
MV1 MVB
CN10 CN12
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 O.U. PCB.
Remove sudden
fluctuation of load
like short path by
discharge air from
the outdoor 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?
Is the connector on
I.U. PCB for
expansion valve
connected properly?
Do the refrigerant
piping and electric
wiring match?
Is refrigerant
correctly charged?
Is gas leaking?
Yes
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 O.U. PCB.
Heating Operation
Cooling Operation
Heating
No
Plug the connectors
(*2) of O.U. PCB
properly.
No
Charge correct
refrigerant volume.
No
Perform self-checking
by O.U. PCB.
Check the expansion
valve.
No
No
No
Match the
refrigerant piping
and electric wiring.
Plug the
connector properly.
Repair leaks of gas.
Correctly charge
refrigerant.
No
Is the opening of the
outdoor unit heat
exchanger's expansion
valve under 8%?
Are the connectors
(*2) of O.U. PCB of
the outdoor unit heat
exchanger's electric
expansion valve
connected properly?
Yes
Yes