
SERVICING
71
PCBHR104
System Troubleshooting
UNITARY DIAGNOSTIC CODES
Symptoms
of Abnormal
Operation
Diagnostic/Status LED
Display Codes
Fault
Description
Possible Causes
Corrective
Actions
Notes & Cautions
Digit 3 Digit
2
Digit 1
• Integrated control
module diagnostic/
status LED display
shows the indicated
code.
BLANK
A
2
• Outdoor air
temp sensor
fault
• Shorted sensor.
• Open sensor
• Sensor
disconnected
• Sensor out of
range
• Check sensor
connection
• Replace open/
shorted sensor
• Turn power OFF prior
to repair.
• Replace with correct
replacement part.
• Heat pump fails to
operate in heating
mode.
• Integrated control
module diagnostic/
status LED display
shows the indicated
code
BLANK
A
3
• Outdoor coil
temp sensor
fault
• Shorted sensor.
• Open sensor
• Sensor
disconnected
• Sensor out of
range
• Check sensor
connection
• Replace open/
shorted sensor
• Turn power OFF prior
to repair.
• Replace with correct
replacement part.
• Air conditioner/
heat pump fails to
operate
• Integrated control
module diagnostic/
status LED display
shows the indicated
code
BLANK
E
5
• Open fuse
• Short in low
voltage wiring
• Locate and
correct short
in low voltage
wiring
• Turn power OFF prior
to repair
• Replace fuse with
3-amp automotive type
• Air conditioner/
heat pump fails to
operate
• Integrated control
module diagnostic/
status LED display
shows the indicated
code
BLANK
E
E
• Board
misoperation
• Compressor relay
contacts welded
• Replace control • Turn power OFF prior
to repair
• Replace with correct
replacement part
• Air conditioner/
heat pump fails to
operate
• Integrated control
module diagnostic/
status LED display
shows the indicated
code
BLANK
b
0
• Circulator
blower
motor is not
running when
it should be
running
• Indoor blower
motor problem
• Communications
error between
indoor and outdoor
unit
• Check indoor
blower motor
• Check indoor
blower motor
wiring
• Check indoor
unit control
• Repair/replace
any faulty wiring
• Repair/replace
indoor blower
motor or control
• Turn power OFF prior
to repair
• Replace with correct
replacement part
• Air conditioner/
heat pump operates
at reduced
performance
• Air conditioner/
heat pump operating
at low stage when
expected to operate
at high stage
• Integrated control
module diagnostic/
status LED display
shows the indicated
code
BLANK
b
9
• Airflow is
lower than
demanded
• Indoor blower
motor problem
• Blocked filters
• Restrictive/
undersized
ductwork
• Indoor/outdoor
unit mismatch
• Check indoor
blower motor
• Check filters;
clean/replace as
needed
• Check
ductwork; resize
as needed
• Verify indoor
and outdoor
units are properly
matched
• Turn power OFF prior
to repair
• Replace with correct
replacement part. See
specification sheet(s)
for airflow requirements
and maximum external
static pressure
• See specification
sheets for approved
system matches
Содержание ASXC16
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