035-14527-000 REV A (599)
Form 650.77-N3U
Unitary Products Group
25
4.
Note the wire/terminal location and then remove the
blower wiring from the furnace control. Remove the pro-
tective boot and disconnect run capacitor wires. Remove
the screws securing the electrical panel to the blower
housing. Pull blower assembly out of the unit. When
cleaning or servicing the blower assembly, DO NOT
remove or change the balance clips on the blower wheel.
5.
To reassemble, reverse the procedure, restore power to
the furnace and verify operation.
Downflow Installations
1.
Disconnect the electrical supply to the furnace and
remove the access doors.
2.
Remove the two wires leading to the auxiliary limit
mounted on the side opposite the blower motor.
3.
Remove four top panel screws and lift the top panel
enough to disengage and remove the flue chase assem-
bly.
4.
Remove blower assembly mounting screws and slide the
blower assembly out of the slots in the deck. If the two
shipping screws were not previously removed, also
remove and discard these two screws located on each
front corner of the blower assembly.
5.
Note the wire/terminal location and then remove the
blower wiring from the furnace control. Remove the pro-
tective boot and disconnect run capacitor wires. Remove
the screws securing the electrical panel to the blower
housing. Pull blower assembly out of the unit. When
cleaning or servicing the blower assembly, DO NOT
remove or change the balance clips on the blower wheel.
6.
To reassemble, reverse the procedure, restore power to
the furnace and verify operation.
Burner Removal/Cleaning
The main burners should be checked periodically for dirt
accumulation.
If cleaning is required, follow this procedure:
1.
Turn off the electrical power to the unit and turn off gas
supply at the shutoff valve.
2.
Remove the blower and burner compartment access
doors.
3.
Unplug ignitor from the wire harness and remove the
ignitor/bracket assembly from the burner air shield. Han-
dle the ignitor carefully as it is fragile and easily broken.
4.
Note the location and then disconnect the sensor and
rollout switch wires located on the top of the air shield
and remove the shield.
5.
Remove the two screws securing each burner to the
burner assembly. Note the orientation of the burner
(flanged side down) before removing. Burners may be
cleaned by rinsing in hot water or by using a vacuum
cleaner.
CLEANING THE HEAT EXCHANGER
Lower Heat Exchanger Access
1.
Turn off the electrical power to the unit and turn off gas
supply at the shutoff valve.
2.
Remove the blower and burner compartment access
doors. Disconnect the gas supply piping at the union to
permit removal of the entire burner and gas control
assembly from the vestibule panel. Use the wrench boss
on the gas valve when removing or installing this piping.
3.
Unplug the ignitor from the wire harness. Disconnect
sensor and rollout switch wires located on top of the air
shield. Identify and note the location of all leads for ease
of reinstallation. Also disconnect the wires at the side
rollout switches (upflow only) and the gas valve wires.
4.
Remove the screws holding the burner assembly to the
vestibule panel and remove this assembly. Handle the
assembly carefully since it contains the ignitor which is
fragile and easily broken. The lower portion of the heat
exchanger will now be exposed. To clean the burner
assembly, use a vacuum cleaner, or remove the burners
as outlined in burner cleaning, and clean in hot water.
Upper Heat Exchanger Access
1.
Perform steps 1-4 above.
2.
Disconnect vent piping from the vent motor assembly at
the top panel on the furnace (upflow only). On downflow
installations this is not necessary.
3.
Unplug the ventor motor wires and ground wire. Remove
the pressure switch tubing at the tap on the ventor motor
housing.
NOTE:
It is recommended that replacement gaskets be avail-
able before removing ventor motor.
4.
Remove six mounting screws that hold the ventor motor
to the restrictor plate. The surface is gasketed and gas-
ket can be reused if it is carefully removed. It is neces-
sary to remove this assembly to gain access to the
restrictor plate mounting holes. The assembly may be
vacuumed if cleaning is necessary. If any vent assembly
parts are damaged, replace with an entire new assembly
(except for gaskets).
5.
Remove the perimeter screws attaching the restrictor
plate assembly to the vestibule panel. The surface is
also gasketed. The assembly, including the flue baffle
plate (rear) may be vacuumed or cleaned with hot water
if necessary.
6.
The upper portion of the heat exchanger is now accessi-
ble. With a long flexible wire brush, clean inside each
tube at both the top and bottom. The brush must pass
