Tools Required - Lennox XC21 Installation Instructions Manual

Charging
The XC21 unit is factory−charged with enough HFC−410A
refrigerant to accommodate a 15−foot length of refrigerant
piping. Charge should be checked and adjusted using the
tables provided on the charging procedure sticker on the
unit access panel. Detailed information is given in the
XC21 Installation and Service Procedures manual, which
is available on DaveNet.
Start−Up Checklists
TWO−STAGE COMPRESSOR PERFORMANCE
Use this procedure to verify part- and full-load capacity op-
eration of the two-stage compressor.
IMPORTANT !
This performance check is ONLY valid on systems that
have clean indoor and outdoor coils, proper airflow over
coils, and correct system refrigerant charge. All
components in the system must be functioning properly
to correctly perform compressor operational check.
(Accurate measurements are critical to this test as
indoor system loading and outdoor ambient can affect
variations between low and high capacity readings).

TOOLS REQUIRED

S Refrigeration gauge set
S Digital volt/amp meter
S Electronic temperature thermometer
S On-off toggle switch
PROCEDURE
1. Turn main power OFF to outdoor unit.
2. Adjust room thermostat set point 5ºF above (heating
operation) or 5ºF below (cooling operation) the room
temperature.
3. Remove control access panel. Install refrigeration
gauges on unit. Attach the amp meter to the common
(black wire) wire of the compressor harness. Attach
thermometer to discharge line as close as possible to
the compressor.
4. Turn toggle switch OFF. Install switch in series with Y2
wire from room thermostat. (See note ** in the Field
Operational Checklist on page 17).
5. Cycle main power ON.
6. Allow pressures and temperatures to stabilize before
taking any reading (may take up to 10 minutes).
7. Record all of the readings for the Y1 demand.
8. Close switch to energize Y2 demand. Verify power is
going to compressor solenoid (see note ** in the Field
Operational Checklist on page 17).
9. Allow pressures and temperatures to stabilize before
taking any reading (may take up to 10 minutes).
10. Record all of the readings with the Y1 and Y2 demand.
11. If temperatures and pressures change in the direction
noted in chart, the compressor is properly modulating
from low to high capacity. (If no amperage, pressures
or temperature readings change when this test is per-
formed, the compressor is not switching between low
and high capacity and replacement is necessary.)
12. After testing is complete, return unit to original set up.
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