Cleaning and/or Replacing Air Filter
NOTE: If the filter has an airflow direction arrow, the arrow must point towards the blower
CAUTION:CUT HAZARD Failure to follow this caution may result in personal injury. Sheet metal parts may have sharp edges or burrs. Use care and wear appropriate protective clothing, safety glasses and gloves when handling parts, and servicing furnaces.
Media cabinet filter procedures:
Blower Motor and Wheel
WARNING: ELECTRICAL SHOCK HAZARD Failure to follow this warning could result in personal injury or death. Blower access door switch opens 115--v power to control. No component operation can occur unless switch is closed. Caution must be taken when manuall
NOTE: The blower wheel should not be dropped or bent as balance will be affected.
The following steps should be performed by a qualified service agency.
To ensure long life and high efficiency, clean accumulated dirt and grease from blower wheel and motor annually
Table 16 – Filter Size Information -- In. (mm)
The inducer and blower motors are pre--lubricated and require no additional lubrication. These motors can be identified by the absence of oil ports on each end of the motor.
Clean blower motor and wheel as follows:
For downflow or horizontal furnaces having vent pipes within the furnace that pass in front of the blower access door:
If a greasy residue is present on blower wheel, remove wheel from the blower housing and wash it with an appropriate degreaser. To remove wheel:
NOTE: Before disassembly, mark blower mounting arms, motor, and blower housing so motor and each arm is positioned at the same location during reassembly.
To check blower for proper rotation:
WARNING: ELECTRICAL SHOCK HAZARD Failure to follow this warning could result in personal injury, or death. Blower access door switch opens 115--v power to furnace control. No component operation can occur unless switch is closed. Exercise caution to avoid
NOTE: If R--W/W1 thermostat terminals are jumpered at the time blower access door switch is closed, blower will run for 90 sec before beginning a heating cycle.
If furnace is operating properly, RELEASE BLOWER ACCESS DOOR SWITCH. Remove any jumpers or reconnect any disconnected thermostat leads. Replace blower access door
Downflow or horizontal furnaces with vent pipe through furnace only:
Cleaning Heat Exchanger
The following steps should be performed by a qualified service agency:
NOTE: If the heat exchangers get a heavy accumulation of soot and carbon, they should be replaced rather than trying to clean them thoroughly. A build--up of soot and carbon indicates that a problem exists which needs to be corrected, such as improper adj
Fig. 54 -- Igniter Position -- Side View
Fig. 55 -- Igniter Position -- Top View
If it becomes necessary to clean the heat exchangers because of dust or corrosion, proceed as follows:
Disconnect wires to the following components. Mark wires to aid in reconnection (be careful when disconnecting wires from switches because damage may occur):
NOTE: Be very careful when removing burner assembly to avoid breaking igniter. See Fig. 54--55 for correct igniter location.
Using field--provided 25--caliber rifle cleaning brush, 36--in. (914 mm) long, 1/4--in. (6 mm) diameter steel spring cable, a variable speed, follows:
NOTE: The materials needed in item 9 can usually be purchased at local hardware stores.
Fig. 56 -- Cleaning Heat Exchanger Cell
NOTE: A releasing agent such as cooking spray or equivalent (must not contain corn or canola oil, aromatic or halogenated hydrocarbons or inadequate seal may occur) and RTV sealant (G.E. 162, 6702, or Dow--Corning 738) are needed before starting installat
Reconnect wires to the following components (Use connection diagram on wiring label, if wires were not marked for reconnection locations.):
WARNING: FIRE OR EXPLOSION HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Never purge a gas line into a combustion chamber. Never test for gas leaks with an open flame. Use a commercially available so
Sequence of Operation
NOTE: Furnace control must be grounded for proper operation or else control will lock out. Control is grounded through green/yellow wire routed to gas valve and burner box screw. Using the schematic diagram in Fig. 53, follow the sequence of operation thr
NOTE: If a power interruption occurs during a call for heat (W/W1 or W/W1--and--W2), the control will start a 90--second blower--only ON period two seconds after power is restored, if the thermostat is still calling for gas heating. The amber LED light wi
The blower door must be installed for power to be conducted through the blower door interlock switch ILK to the furnace control CPU, transformer TRAN, inducer motor IDM, blower motor BLWM, hot--surface igniter HSI, and gas valve GV
NOTE: The low--heat only switch SW1--2 selects either the low--heat only operation mode when ON, (see item 2. below) or the adaptive heating mode when OFF in response to a call for heat. (See Table 10.) When the W2 thermostat terminal is energized it will
This furnace can operate as a two--stage furnace with a single--stage thermostat because the furnace control CPU includes a programmed adaptive sequence of controlled operation, which selects low--heat or high--heat operation. This selection is based upon
If the power is interrupted, the stored history is erased and the control CPU will select low--heat for up to 16 minutes and then switch to high--heat, as long as the thermostat continues to call for heat. Subsequent selection is based on stored history o
a. Inducer Prepurge Period