Johnson Controls YVAHP0721CW Series, Service Manual

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3-64
SM-16007
TROUBLESHOOTING
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The indoor unit number and the alarm code are displayed on the LCD. The alarm code is displayed on
the 7-segment display of the outdoor unit PCB.
+
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the thermistor is detected during a heating or cooling operation.
NOTE:
This DOAS has function using both Remote Thermistor (THM4) and Thermistor for Controller.
While operating by this function,
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measured from an available Thermistor,
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For this reason, when both Remote Thermistor (THM4) and Thermistor for Controller are using
and this alarm code is displayed means both of Thermistor are failure. As for Remote Thermistor
(THM4), follow the previous page, “Alarm Code 16: Abnormality of Remote Thermistor (DOAS)”
for checking.
Refer to "Alarm Code 11"
for thermistor resistance.
Failure of I.U. PCB
Yes
Failure of Thermistor for Controller
No
Is resistance of Thermistor for Controller
between 0.24k
Ω
and 840k
Ω
?
Cause Check Item
Action
(Turn OFF Main Switch)
Event
Failure of
Thermistor for
Controller
Check short-circuit and
disconnection wiring. Replace controller
if faulty.
Failure
Replace I.U. PCB
and check operation. Replace I.U. PCB
if faulty.
Failure of I.U. PCB
Alarm
Code
Abnormality of Thermistor for Controller
(for DOAS Unit)