SERVICING
78
PCBHR105
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
Summary of Contents for ASXC16
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