Cleaning Heat Exchangers; Primary Heat Exchangers - Carrier 58MCB Service And Maintenance Instruction

→ Fig. 7—Igniter Wire Placement
PRIMARY HX
INLET OPENINGS
Fig. 8—Cleaning Inlet Openings of Primary Heat
Exchangers
FIRE, EXPLOSION, UNIT DAMAGE HAZARD
Failure to follow this warning could result in property
damage, personal injury, or death.
Gas valve switch MUST be facing forward or tilted upward.
19. Replace burner box cover.
20. Turn on gas and electrical supplies to furnace.
→
FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result in
serious injury, death, or property damage.
Never test for gas leaks with an open flame. Use a commer-
cially available soap solution made specifically for the
detection of leaks to check all connections.
21. Check for gas leaks.
IGNIT ER WIRES MUST
BE PLACED IN THIS SLOT
A05074
A96305
RTV
Fig. 9—Combustion-Air Intake Housing Gasket
22. Replace main furnace door.
Step 4—Cleaning Heat Exchangers
The following items should be performed by a qualified service
technician.

PRIMARY HEAT EXCHANGERS

If the heat exchangers get an accumulation of light dirt or dust on
the inside, they may be cleaned by the following procedure:
NOTE: If the heat exchangers get a heavy accumulation of soot
and carbon, both the primary and secondary heat exchangers
should be replaced rather than trying to clean them thoroughly due
to their intricate design. A build-up of soot and carbon indicates
that a problem exists which needs to be corrected, such as
improper adjustment of manifold pressure, insufficient or poor
quality combustion air, improper vent termination, incorrect size
or damaged manifold orifice(s), improper gas, or a restricted heat
exchanger (primary or secondary). Action must be taken to correct
the problem.
1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
→
UNIT DAMAGE HAZARD
Failure to follow this caution may result in furnace compo-
nent damage.
Label all wires prior to disconnection when servicing con-
trols. Wiring errors can cause improper and dangerous
operation.
3. Disconnect wires or connectors to flame rollout switch, gas
valve, igniter, and flame sensor.
4. Disconnect combustion-air intake pipe from intake housing.
5. Remove the pressure switch tube from intake housing.
6. Remove screws attaching intake housing to burner box, and
rotate intake housing away from burner box for removal.
7. Using backup wrench, disconnect gas supply pipe from gas
valve.
8. Disconnect pressure tubing from gas valve.
9. Remove 2 screws attaching top filler panel and rotate upwards
to gain access to screws attaching burner box to cell panel.
10. Remove screws attaching burner box to cell panel. (See Fig.
6.)
NOTE: Burner box, cover, manifold, gas valve, and burner
assembly should be removed as 1 assembly.
11. Clean heat exchanger openings with a vacuum and a soft
brush. (See Fig. 8.)
6
PAM
Repair
A93087