SERVICING
26
Air Handler Troubleshooting Matrix
Symptoms of Abnormal
Operation
Diagnostic
/ Status
LED Codes
Fault Description
Possible Causes
Corrective Actions
No outdoor unit operations
Communication error
with outdoor unit
Improper low voltage wiring
between the indoor and
outdoor unit
Outdoor control board lost
power during operation
Locate and correct improper low
voltage wiring Issue
Identify reason outdoor control
board lost power during operation
No Air Handler operation
Open fuse
Short in low voltage wiring
Locate and correct short in low
voltage wiring
Replace fuse with 3-amp automotive
type
No Air Handler operation
Auxiliary switch
(condensate switch)
open
High water level in the
evaporation coil
Check evaporator drain pan, trap,
piping
No Air Handler operation
Data not yet on network
No network data
Populate shared data set using
memory card
No Air Handler operation
Invalid memory card data
Air Handler blower does not
contain an appropriate shared
data set
Populate correct shared data using
memory card
Operation different than expected
or no operation
Invalid memory card data
Shared data set on memory
card has been rejected by
integrated control module
Verify shared data set is correct for
the specific model. Re-populate data
using correct memory card if required
No Air Handler operation
Circulator blower motor
not running with demand
present
Loose or disconnected wiring
connection at circulator
motor power leads
Open circuit in inductor or
loose wiring connection at
inductor (3/4 Hp and 1 Hp
models only)
Failed circulator blower motor
Tighten or correct wiring connection
Verify continuous circuit through
inductor
Replace if open or short circuit
Check circulator blower motor
No Air Handler operation
Integrated control
module has lost
communications with
circulator blower motor
Loose wiring connection at
circulator motor control leads
Failed circulator blower motor
Failed integrated control
module
Tighten or correct wiring connection
Check circulator blower motor,
replace if necessary
Check integrated control module,
replace if necessary
No Air Handler operation
Circulator blower motor
horse power in shared
data set does not match
circulator blower motor
horse power
Incorrect circulator blower
motor in Air Handler
Incorrect shared data set in
integrated control module
Verify circulator blower if motor
horse power is the same specified
for the specific Air Handler model,
replace if necessary
Verify shared data set is correct for
the specific model, re-populate data
using correct memory card if required
Air Handler operates at reduced
performance
Airflow delivered is less than
expected
Circulator blower motor
is operating in a power,
temperature, or speed
limiting condition
Blocked filters
Restrictive or undersized
ductwork
High ambient temperatures
Check filters for blockage, clean
filters or remove obstruction
Check ductwork for blockage,
remove obstruction and verify all
registers are fully open
Verify ductwork is appropriately sized
for system and resize/replace ass
needed
