Carrier 48FC M20 Series Service And Maintenance Instructions page 41

REMOVING THE HEAT EXCHANGER
The following procedure details the steps to remove the heat ex-
changed from the unit.
1. Turn off electric power to the unit and shut off the unit's
gas supply.
2. Remove the two exterior panels: control box access panel
and indoor blower access panel.
3. Remove the unit center post (see Fig. 53).
4. Disconnect the two wires from the gas limit switch.
5. Remove the three interior panels: control box high voltage
panel, burner partition panel, and heat exchanger cover panel.
6. Disconnect the wires connected to the gas valve. Mark
each wire.
7. Disconnect the igniter wires and sensor wires at the inte-
grated gas controller (IGC).
Low Heat
Medium Heat
High Heat
Detail B
Detail A
Detail A
Detail A
3.05 mm (0.12 in.)
3.56 mm (0.14 in.)
SPARK GAP
Fig. 55 — Spark Adjustment
41
8. Disconnect a gas pipe union and remove the gas manifold
with the gas valve.
9. Remove the two screws attaching the burner rack to the
vestibule plate (see Fig. 49).
10. Remove the pressure switch hose from the connection on
the flue cover assembly (see Fig. 49).
11. Remove the screws around the vestibule plate.
12. Remove the nuts holding the heat exchanger support rack
to the fan deck (see Fig. 51).
13. Remove the heat exchanger from the unit.
14. Separate the following from the heat exchanger: inducer
fan-motor assembly, flue cover assembly, retainer, regula-
tor, and regulator gasket.
Rollout Switch
Rollout Switch
Rollout Switch
4.6 mm (0.18 in.)
Detail A
Detail B
Detail B
Detail B