Maintenance; User Information - Lennox XP14 Elite Series Installation Instructions Manual

Enter the TEST mode by placing a shunt (jumper) across
the TEST pins on the board after power−up. The TEST
pins are ignored and the test function is locked out if the
shunt is applied on the TEST pins before power−up. Board
timings are reduced, the low−pressure switch is ignored
and the board will clear any active lockout condition.
NOTE − The 30−second off cycle is NOT functional when
jumpering the TEST pins.
Ambient Sensor The ambient sensor (shown in figure
26) considers outdoor temperatures below −35°F (−37°C)
or above 120°F (48°C) as a fault. If the ambient sensor is
detected as being open, shorted or out of the temperature
range of the sensor, the board will not perform demand
defrost operation. The
time/temperature defrost operation and will display the
appropriate fault code. Heating and cooling operation will
be allowed in this fault condition.
Coil Sensor The coil temperature sensor (shown in
figure 26) considers outdoor temperatures below −35°F
(−37°C) or above 120°F (48°C) as a fault. If the coil
temperature sensor is detected as being open, shorted or
out of the temperature range of the sensor, the board will
not perform demand or time/temperature defrost
operation and will display the appropriate fault code.
Heating and cooling operation will be allowed in this fault
condition.
OPERATIONAL DESCRIPTION
The defrost control board has three basic operational
modes: normal, calibration, and defrost.
Normal Mode The demand defrost board monitors the
O line, to determine the system operating mode
(heat/cool), outdoor
temperature (outdoor coil) and compressor run time to
determine when a defrost cycle is required.
Calibration Mode The board is considered uncalibrated
when power is applied to the board, after cool mode
operation, or if the coil temperature exceeds the
termination temperature when it is in heat mode.
Calibration of the board occurs after a defrost cycle to
ensure that there is no ice on the coil. During calibration,
the temperature of both the coil and the ambient sensor
are measured to establish the temperature differential
which is required to allow a defrost cycle.
Defrost Mode The following paragraphs provide a
detailed description of the defrost system operation.
DETAILED DEFROST SYSTEM OPERATION
Defrost Cycles The demand defrost control board
initiates a defrost cycle based on either frost detection or
time.
S
Frost Detection If the compressor runs longer than
30 minutes and the actual difference between the clear
coil and frosted coil temperatures exceeds the
maximum difference allowed by the control, a defrost
cycle will be initiated.
505244M 10/09
board will revert
ambient temperature,
IMPORTANT − The demand defrost control board will
allow a greater accumulation of frost and will initiate
fewer defrost cycles than a time/temperature defrost
system.
S
Time If six hours of heating mode compressor run
time has elapsed since the last defrost cycle while the
coil temperature remains below 35°F (2°C), the
demand defrost control will initiate a defrost cycle.

Maintenance

to
Before the start of each heating and cooling season, the
following service checks should be performed by a
qualified service technician. First, turn off electrical power
to the unit prior to performing unit maintenance.
S
Inspect and clean the outdoor and indoor coils. The
outdoor coil may be flushed with a water hose.
NOTE − It may be necessary to flush the outdoor coil
more frequently if it is exposed to substances which
are corrosive or which block airflow across the coil
(e.g., pet urine, cottonwood seeds, etc.)
S
Visually inspect the refrigerant lines and coils for leaks.
S
Check wiring for loose connections.
S
Check voltage at the indoor and outdoor units (with
units operating).
coil
S
Check the amperage draw at the outdoor fan motor,
compressor, and indoor blower motor. Values should
be compared with those given on unit nameplate.
S
Check, clean (or replace) indoor unit filters.
S
Check the refrigerant charge and gauge the system
pressures.
S
Check the condensate drain line for free and
unobstructed flow; clean, if necessary.
S
Adjust blower speed for cooling. Measure the pressure
drop over the coil to determine the correct blower CFM.
Refer to the unit information service manual for pressure
drop tables and procedure.
NOTE − If owner reports insufficient cooling, the unit
should be gauged and refrigerant charge checked.
Refer to section on refrigerant charging in this
instruction.

User Information

MAINTENANCE
In order to ensure peak performance, your system must be
properly maintained. Clogged filters and blocked airflow
prevent your unit from operating at its most efficient level.
1. Air Filter Ask your Lennox dealer to show you where
your indoor unit's filter is located. It will be either at the
indoor unit (installed internal or external to the cabinet)
Page 24
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.