Carrier DELUXE 58DXC - Manual (Page 4)

b. Reinstall vent pipe enclosure.
c. Reconnect red wires to auxiliary limit switch.
20. Connect electrical leads to blower speed selector. Note that
connections are polarized for correct assembly — do not force.
21. Turn ON electrical supply and check for proper rotation and
speed changes between heating and cooling; operate unit 5
minutes and carefully check for condensate leaks.
Step 3—Cleaning Heat Exchangers
The following items should be performed by a qualified service
technician:
If it becomes necessary to clean the heat exchanger because of
carbon deposits, soot, etc., proceed as follows:
NOTE: Deposits of soot and carbon indicate a problem exists that
needs to be corrected. Action must be taken to correct the problem.
1. Turn OFF gas and electrical supplies to furnace.
2. Remove control and blower access doors.
3. Loosen hose clamps on combustion-air pipe and move air pipe
aside.
4. Using backup wrench, disconnect gas supply at ground joint
union. Remove gas pipe from valve.
5. Disconnect hot surface ignitor and flame sensor leads at
3-circuit connector outside of burner enclosure.
6. Disconnect electrical wires from gas valve.
7. Disconnect pressure tubing from right side of burner enclosure
and outlet end of gas valve.
8. Remove burner enclosure front.
9. Remove diffuser from inside top of burner enclosure. Remove
screws that secure burner enclosure to cell panel. These
screws are located inside the burner enclosure.
10. Using care not to damage cell inlet panel gasket, remove gas
control assembly from furnace.
11. Remove vent pipe and drain.
a. Upflow furnace only:
(1.) Loosen hose clamps at vent pipe connection; discon­
nect vent pipe and position to 1 side.
(2.) Loosen hose clamp and remove drain tube from
inducer outlet box.
b. Downflow furnace only:
(1.) Remove vent pipe enclosure.
(2.) Loosen hose clamps at vent pipe connection.
(3.) Loosen hose clamp and remove drain tube from
inducer outlet elbow.
12. Upflow furnace only —remove main control box.
a. Disconnect edge connector from main control box at
blower shelf.
b. Remove screws securing main control box to blower shelf
and position control box to 1 side.
13. Disconnect inducer motor connector from wiring harness.
Disconnect wires and pressure tube from pressure switch.
14. Loosen hose clamp and remove drain tube from inducer
housing.
15. Remove mounting screws securing inducer assembly to col­
lector box and coupling box; remove inducer assembly.
16. Remove all old sealant from parts.
17. Remove coupling box(es).
a. Upflow furnace only:
(1.) Remove screws securing coupling box and remove
from furnace. Remove all old sealant from parts.
(2.) Remove choke plate (when used) from primary heat
exchanger outlet.
b. Downflow furnace only:
(1.) Remove screws securing intake (upper) coupling box
and remove from furnace. Remove all old sealant from
parts. ^
(2.) Remove screws securing primary (lower) coupling
box and remove box. Clean old sealant from parts.
18. Loosen hose clamp and remove 7/8-in. drain tube from trap.
19. Hold bucket under 7/8-in. drain tube.
20. Using garden hose, flush each cell of the condensing heat
exchanger with water. Use care not to spray water onto
interior surfaces of control compartment. Dry all surfaces. Be
careful not to remove sealant around cell openings in cell
panel.
21. Using field-provided small wire brush, steel spring cable,
reversible electric drill, and vacuum cleaner, clean primary
heat exchanger cells. Do not use wire brush or other sharp
object to clean condensing heat exchanger. Failure of the
condensing heat exchanger will occur—flush with water only.
a. Assemble wire brush and steel spring cable.
(1.) Use 4 ft of 1/4-in. diameter high-grade steel spring
cable (commonly known as drain cleaning or Roto-
Rooter cable).
(2.) Use 1/4-in. diameter wire brush (commonly known as
25-caIiber rifle cleaning brush).
NOTE: The materials required in items (1.) and (2.) can be
purchased at local hardware stores.
(3.) Insert twisted wire end of brush into end of spring
cable, and crimp tight with crimping tool or strike with
ball-peen hammer. Tightness is very important.
(4.) Remove metal screw fitting from wire brush to allow
insertion into cable.
b. Clean each primary heat exchanger cell.
(1.) Attach variable-speed, reversible drill to end of spring
cable (end opposite brush).
(2.) Insert brush end of cable into upper opening of cell
and slowly rotate with drill. Do not force cable.
Gradually insert at least 3 ft of cable into 2 upper
passes of cell. (See Fig. 7.)
A884S9
Fig. 7—Cleaning Primary Heat Exchanger Cell
(3.) Work cable in and out of cell 3 or 4 times to obtain
sufficient cleaning. Do not pull cable with great force.
Reverse drill and gradually work cable out.
(4.) Insert brush end of cable in lower opening of cell, and
proceed to clean 2 lower passes of cell in same manner
as 2 upper passes.