Page 44
XP16
TWO−STAGE MODULATION COMPRESSOR
CHECKS
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 proper to
correctly perform compressor modulation 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).
Use this checklist on page to verify part-load and full-load
capacity operation of two-stage modulation compressors.
TOOLS REQUIRED
D
Refrigeration gauge set
D
Digital volt/amp meter
D
Electronic temperature thermometer
D
On-off toggle switch
PROCEDURE
NOTE − Block outdoor coil to maintain a minimum of 375 psig
during testing).
1
. Turn main power OFF to outdoor unit.
2
. Adjust room thermostat set point 5ºF above 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 and install switch in series with
Y2 wire from room thermostat.
5
. Cycle main power ON.
6
. Allow pressures and temperatures to stabilize before
taking measurements (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.
9
. Allow pressures and temperatures to stabilize before
taking measurements (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 Two−Stage Modulation Compressor Field
Operational Checklist on page , the compressor is
properly modulating from low to high capacity. (If no
amperage, pressures or temperature readings change
when this test is performed, the compressor is not
modulating between low and high capacity and
replacement is necessary).
12
. After testing is complete, return unit to original set up.
Maintenance
WARNING
Electric shock hazard. Can cause injury or
death. Before attempting to perform any
service or maintenance, turn the electrical
power to unit OFF at disconnect
switch(es). Unit may have multiple power
supplies.
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause personal injury, loss of life, or
damage to property.
Installation and service must be performed by a licensed
professional installer (or equivalent) or a service agency.
Maintenance and service must be performed by a qualified
installer or service agency. At the beginning of each cooling
season, the system should be checked as follows:
