Instructions / Assembly
16
Table 2. Filter Sizes
CABINET SIZE FILTER SIZE
A 12 x 20 x 1
B 18 x 20 x 1
C 20 x 20 x 1
RED LED (AN2) DIAGNOSTIC
OFF Control Fault (No Power)
Flash Blower Fault
ON Normal Operation
Table 3. Air handler Control Board Fault Conditions
UNIT MAINTENANCE
Proper maintenance is most important to achieve the best 
performance from a air handler. Some of the components 
and their locations are shown in Figure 12 (page 18). If 
any component of the air handler must be replaced, use 
only factory authorized replacement parts specified in the 
Replacement Parts List provided online.
 WARNING:
ELECTRICAL SHOCK, FIRE OR
EXPLOSION HAZARD
Failure to follow safety warnings exactly could 
result in serious injury or property damage.
Improper servicing could result in dangerous 
operation, serious injury, death or property 
damage.
• Beforeservicing,disconnectallelectricalpower
to the indoor blower.
• Whenservicingcontrols,labelallwiresprior
to disconnecting. Reconnect wires correctly.
• Verifyproperoperationafterservicing.
• Thesemaintenanceinstructionsareprimarilyintended
to assist qualified technicians experienced in the proper 
maintenance and operation of this appliance.
• Always reinstall the doors on the air handler after
servicing or cleaning/changing the filters. Do not operate 
the air handler without all doors and covers in place.
• Verifythatthethermostatisproperlyinstalledandis
not being affected by drafts or heat from lamps or other 
appliances.
• To achieve the best performance and minimize
equipment failure, it is recommended that a yearly 
maintenance checkup be performed. At a minimum, 
this check should include the following items:
Air Filter(s) - B6 Series Air Handlers are not supplied 
with a single air filter when shipped from the factory. It 
is recommended that the filter be cleaned or replaced 
every 4 to 6 months at a minimum. Newly built or recently 
renovated homes may require more frequent changing 
until the construction dust has minimized. Filter sizes 
shown in Table 2 are available at most local retailers.
 WARNING:
Never operate the air handler without a filter in 
place. Dust and lint in the return air can build 
up on internal components, resulting in loss of 
efficiency, equipment damage, and possible fire.
Filters designed to remove smaller particles such as 
pollen, may require additional maintenance.
Blower Compartment - Dirt and lint can create excessive 
loads on the motor resulting in higher than normal 
operating temperatures and shortened service life. It is 
recommended that the blower compartment be cleaned of 
dirt or lint that may have accumulated in the compartment 
or on the blower and motor as part of the annual inspection.
Blower Fan Wheel - Inspect the blower wheel blades 
for accumulations of dirt and clean if necessary. Inspect 
mounting nut for tightness when done.
Blower Motor & Assembly - Inspect the blower assembly 
and motor mounting brackets for tightness and corrosion. 
Correct deficiencies if necessary. The blower motor 
contains sealed bearings and under normal operating 
conditions, no maintenance is necessary for the life of 
the equipment.
TROUBLESHOOTING
If the air handler fails to operate, check the following:
• Istheelectricturnedon?
• Isthethermostatoperatingproperly?
• Aretheblowercompartmentdoor(s)inplace?
• Istheairhandlerdisconnectclosed?
• Hasthecircuitbreakertrippedorthecontrolboardfuse
burnedopen?
• Areanymanualresetswitchesopen?
• Isthelterdirtyorplugged?
• IstheLEDonbothcontrolboardsconstantlyON?Ifnot,
refer to Table 3 or Table 4 to determine fault condition.
Table 4. Motor Control Board Fault Conditions
DIAGNOSTIC
GREEN
LED
RED
LED
FIXED
SPEED
FURNACES
Control Fault (no Power) Off Off
normal oPeration On On
motor Fault On Flash
twin Fault (no motor Fault) Flash On
CommuniCations Fault Flash Flash
VARIABLE
SPEED
FURNACES
Control Fault (no Power) Off Off
normal oPeration On On
motor Fault On Flash
CommuniCations Fault Flash Flash










