Carrier 48NLT - Manual (Page 24)

Heating Section — Ensure dependable and efficient
heating operation by inspecting the heating section before
each heating season, and cleaning when necessary.
Proceed as follows to inspect and clean heating section:
1. Turn off gas and power to unit.
2. Remove burner access door.
3. Disconnect 2 wires from inducer motor.
4. Remove complete inducer assembly from unit.
5. Remove screws that secure collector box to heat ex­
changer, exposing flue openings.
6. Remove flue choke.
7. Clean heat exchanger cells using field-provided small
wire brush, steel spring cable, reversible electric drill
and vacuum cleaner.
To assemble wire brush and steel spring cable:
NOTE: The items below can be purchased at a local
hardware store.
a. Use 4 ft of Vi in. diameter high-grade steel spring
cable (commonly known as drain cleanout or Roto-
Rooter cable).
b. Use Vi-in. diameter wire brush (commonly known
as 25-caliber rifle cleaning bmsh).
c. Insert twisted wire end of brush into end of spring
cable; crimp tight with crimping tool or strike with
ball-peen hammer.
Tightness is very important.
d. Remove metal sleeve from wire brush to allow proper
brush action.
To clean each heat exchanger cell:
a. Attach variable-speed reversible drill to end of spring
cable (end opposite brush).
b. 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.
c. 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.
d. Remove burner assembly.
e. Insert brush end of cable in lower opening of cell
and proceed to clean in same manner.
f. Repeat above procedures until each cell in unit is
cleaned.
g. Using vacuum cleaner, remove residue from each
cell.
h. Using vacuum cleaner with soft brush attachment,
clean burner assembly.
i. Reinstall burner assembly.
8. After cleaning, check sealant and gaskets to make sure
that they have not been damaged. If new sealants or
gaskets are needed, contact your Distributor.
9. Reinstall flue choke. Be sure all screws are in and are
tight.
10. Clean and replace flue collector assembly, making sure
all screws are secure.
11. Replace inducer assembly.
12. Reconnect the 2 wires to inducer motor.
13. Replace burner access door.
14. Turn on power and gas.
15. Set thermostat and check unit for proper operation.
Pilot — Inspect the pilot and clean (when necessary) at
the beginning of each heating season. Remove the accumu­
lation of soot and carbon from the pilot. The pilot flame
must be high enough for proper contact with the flame sen­
sor. Pilot flame must also come in contact with the pilot
hood (target) for proper operation. If the pilot flame ap­
pears too hard (lifting and blowing) or too soft (unstable),
check inlet gas pressure for proper value. (See Table 4.)
The spark electrode must be located so the spark travels
through a combustible mixture of gas; if necessary, readjust
the electrode as shown in Fig. 15; be certain to maintain the
Vs-in. spark gap.
TARGET
Fig. 15 — Position of Electrode to Pilot
Condenser Coil, Evaporator Coil and Conden­
sate Drain Pan
— Inspect the condenser coil, evapo­
rator coil and condensate drain pan at least once each year.
Proper inspection and cleaning requires the removal of the
unit top. See Unit Top Removal section.
The coils are easily cleaned when dry; therefore, inspect
and clean the coils either before or after each cooling sea­
son. Remove all obstructions, including weeds and shrubs,
that interfere with the airflow, through the condenser coil.
Straighten bent fins with a fin comb. If coated with dirt or
lint, clean the coils with a vacuum cleaner, using the soft
brush attachment. Be careful not to bend the fins. If coated
with oil or grease, clean the coils with a mild detergent-
and-water solution. Rinse coils with clear water, using a
garden hose. Be careful not to splash water on motors, in­
sulation, wiring or air filter(s). For best results, spray con­
denser coil fins from inside to outside the unit. On units
with an outer and inner condenser coil, be sure to clean be­
tween the coils. Be sure to flush all dirt and debris from the
unit base.
Inspect the drain pan and condensate drain line when in­
specting the coils. Clean the drain pan and condensate drain
by removing all foreign matter from the pan. Flush the pan
and drain tube with clear water. Do not splash water on the
insulation, motor, wiring or air filter(s). If the drain tube is
restricted, clear it with a “plumbers snake” or similar probe
device.
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