Specifications are subject to change without notice.
441 01 3700 00
45
a. Remove metal screw fitting from wire brush to allow
insertion into cable.
b. Insert the twisted wire end of brush into end of spring
cable, and crimp tight with crimping tool or crimp by
striking with ball--peen hammer. TIGHTNESS IS
VERY IMPORTANT.
NOTE
: The materials needed in item 9 can usually be purchased
at local hardware stores.
(1.) Attach variable--speed, reversible drill to the end
of spring cable (end opposite brush).
(2.) Insert brush end of cable into the outlet opening
of cell and slowly rotate with drill. DO NOT
force cable. Gradually insert cable into upper pass
of cell. (See Fig. 51.)
(3.) Work cable in and out of cell 3 or 4 times to ob-
tain sufficient cleaning. DO NOT pull cable with
great force. Reverse drill and gradually work ca-
ble out.
(4.) Insert brush end of cable in burner inlet opening
of cell, and proceed to clean 2 lower passes of
cell in same manner as upper pass.
(5.) Repeat foregoing procedures until each cell in
furnace has been cleaned.
(6.) Using vacuum cleaner, remove residue from each
cell.
(7.) Using vacuum cleaner with soft brush attachment,
clean burner assembly.
(8.) Clean flame sensor with fine steel wool.
A91252
Fig. 51 -- Cleaning Heat Exchanger Cell
(9.) Reinstall burner assembly. Center burners in cell
openings.
10. Remove old sealant from cell panel and collector box
flange.
11. Spray releasing agent on the heat exchanger cell panel
where collector box assembly contacts cell panel.
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 installation. DO NOT substitute any other type of RTV
sealant.
12. Apply new sealant to flange of collector box and attach to
cell panel using existing screws, making sure all screws
are secure.
13. Reconnect wires to the following components (Use con-
nection diagram on wiring label, if wires were not marked
for reconnection locations.):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switches.
d. Limit overtemperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame--sensing electrode.
h. Flame rollout switches.
14. Reinstall internal vent pipe, if applicable.
15. Reinstall vent connector on furnace vent elbow. Securely
fasten vent connector to vent elbow with 2 field--supplied,
corrosion--resistant, sheet metal screws located 180
_
apart.
16. Replace blower access door only if it was removed.
17. Set thermostat above room temperature and check furnace
for proper operation.
18. Verify blower airflow and speed changes between heating
and cooling.
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 soap solution made specifically for the detection
of leaks to check all connections. A fire or explosion may
result causing property damage, personal injury or loss of
life.
!
WARNING
19. Check for gas leaks.
Sequence of Operation
NOTE
: Furnace control must be grounded for proper operation
or control will lock out. Control is grounded through
green/yellow wire routed to gas valve and manifold bracket
screw.
Using the schematic diagram, follow the sequence of operation
through the different modes. Read and follow the wiring diagram
very carefully.
NOTE
: If a power interruption occurs during a call for heat (W),
the control will start a 90--sec blower--only ON period two
seconds after power is restored, if the thermostat is still calling for
gas heating. The LED light will flash code 1+2 during the 90--sec
period, after which the LED will be flashing a heartbeat, as long
as no faults are detected. After the 90--sec period, the furnace will
respond to the thermostat normally.
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.
1.
Heating
The wall thermostat “calls for heat,” closing the R--to--W
circuit. The furnace control performs a self--check, verifies
the pressure switch contacts PRS are open, and starts the
inducer motor IDM.
a.
Inducer Prepurge Period
-- The inducer enable relay
contacts IDR close and allow 115 VAC to inducer mo-
tor and
HUM
terminal. As the inducer motor IDM
comes up to speed, the pressure switch contacts PRS
close, 24 VAC power is supplied for a field installed
humidifier at the 24VAC HUM terminal and the con-
trol begins a 15--sec prepurge period.
b.
Igniter Warm--Up
-- At the end of the prepurge period,
the Hot--Surface igniter HSI is energized for a 17--sec-
ond igniter warm--up period.
c.
Trial--for--Ignition Sequence
-- When the igniter
warm--up period is completed, the main gas valve re-
lay contacts GVR close to energize the gas valve GV,
the gas valve opens, The gas valve GV permits gas
flow to the burners where it is ignited by the HSI. Five
seconds after the GVR closes, a 2--second flame prov-
ing period begins. The HSI igniter will remain ener-
gized until the flame is sensed or until the 2--second
flame proving period begins.
