Carrier 48NLT - Page 25

Condenser Fan
A CAUTION
Keep the condenser fan free from all obstructions to
ensure proper cooling operation. Never place articles
on top of the unit. Damage to unit may result._
Remove control and compressor access panels. Inspect
the fan blades for cracks or bends each year. Make sure
that blades clear the motor by no more than V4 inch. If the
blade assembly has slipped down the motor shaft, adjust
the fan position on the motor shaft by loosening the set-
sere w(s), then moving the blade assembly up. Be sure that
the setscrew(s) is on the flat(s) of the motor shaft before
tightening.
Electrical Controls and Wiring — Inspect and check
the electrical controls and wiring annually. Be sure to turn
off the gas supply, and then the electrical power to the unit.
Remove the control, blower and compressor compart¬
ment access panels to locate all the electrical controls and
wiring. Check all electrical connections for tightness. Tighten
all screw connections. If any smoky or burned connections
are noticed, disassemble the connection, clean all the parts,
restrip the wire end and reassemble the connection properly
and securely.
After inspecting the electrical controls and wiring, re¬
place all the panels. Start the unit, and observe at least one
complete heating cycle and one complete cooling cycle to
ensure proper operation. If discrepancies are observed in
either or both operating cycles, or if a suspected malfunc¬
tion has occurred, check each electrical component with the
proper electrical instrumentation. Refer to the unit wiring
label when making these checkouts.
NOTE: Refer to the heating and/or cooling sequence of op¬
eration in this publication as an aid in determining proper
control operation.
RGfrigerant Circuit — Inspect all refrigerant tubing con¬
nections and the unit base for oil accumulations annually.
Detecting oil generally indicates a refrigerant leak.
If oil is detected or if low cooling performance is sus¬
pected, leak-test all refrigerant tubing using an electronic
leak-detector, or liquid-soap solution. If a refrigerant leak
is detected, refer to Start-Up, Check for Refrigerant Leaks
section.
If no refrigerant leaks are found and low cooling perfor¬
mance is suspected, refer to Checking and Adjusting Re¬
frigerant Charge section.
Gas Input — The gas input does not require checking
unless improper heating performance is suspected. If a prob¬
lem exists, refer to Start-Up section.
Evaporator Airflow — The heating and/or cooling air¬
flow does not require checking unless improper perfor¬
mance is suspected. If a problem exists, be sure that all
supply- and return-air grilles are open and free from ob¬
structions, and that the air filter is clean. When necessary,
refer to Indoor Airflow and Airflow Adjustment section to
check the system airflow.
Metering Device Servicing — See Fig. 16 for me¬
tering device components. The piston has a refrigerant me¬
tering orifice through it. The retainer forms a sealing sur¬
face for liquid line flare connection. To check, clean or replace
piston:
1. Shut off power to unit.
2. Remove refrigerant from unit using approved refrigerant
removal methods from both high- and low-service port
connections.
3. Remove liquid line flare connections from metering
device.
4. Note position of arrow on metering device body with
respect to unit.
5. Pull retainer out of body. Be careful not to scratch flare
sealing surface. If retainer does not pull out easily, care¬
fully use locking pliers to remove retainer. Replace
scratched or damaged retainer.
6. Slide piston out by inserting a small, soft wire through
metering hole (18-gage thermostat wire). See that me¬
tering hole, sealing surface around piston cones and fluted
portion of piston are not damaged.
7. Use the chart on the unit access panel to determine proper
arrangement and size of piston. See Table 13 for piston
sizes.
8. Clean piston refrigerant-metering orifice.
9. Replace retainer 0-ring (part no. 99CC501052).
Liquid Line Strainer — The liquid line strainer (t<
protect metering device) is made of wire mesh and locate*
in the liquid line on inlet side. Strainer is pressed into th
line. Remove strainer by threading a no. 10 sheet-metal scre>
into strainer and pulling the screw with pliers.
FLARE NLfT STRAINER RETAINER COOLING
FLARE
NUT
Fig. 16 ~ Metering Device Components
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