Johnson Controls YVAHP0721CW Series, Service Manual

Page: 224 / 416

3-60
SM-16007
TROUBLESHOOTING
Alarm
Code
Abnormality of Thermistor for Liquid Refrigerant Pipe Temperature
at Indoor Unit Heat Exchanger (Freeze Protection Thermistor)
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.
+
7KLVDODUPFRGHLVGLVSOD\HGZKHQDVKRUWFLUFXLWNȍRUOHVVRUGLVFRQQHFWLRQNȍRUPRUHRI
the thermistor is detected during a heating or cooling operation. The operation automatically restarts
when the malfunction is removed.
Yes
Connect them.
No
Refer to "Alarm Code 11"
for thermistor resistance.
Is thermistor THM3
(for freeze protection)
connected to THM3 of
I.U. PCB?
Yes
No
Is resistance of THM3
between 0.24k
Ω
and
840k
Ω
?
Failure of I.U. PCB
Failure of
Thermistor
Cause Check Item
Action
(Turn OFF Main Switch)
Event
Failure of
Freeze Protection
Thermistor
Check resistance.
Replace thermistor
if faulty.
Failure
Check wiring to
I.U. PCB.
Correctly connect wires.
Incorrect Connection
Replace I.U. PCB
and check operation. Replace I.U. PCB
if faulty.
Failure of I.U. PCB
Liquid Pipe Thermistor
(Freeze Protection)
Example of 4-way Cassette Type