Time Delay; Diagnostic Leds - Lennox Elite XP13-024 Installation Instructions Manual

removed before an additional 5-second period has
elapsed (7 seconds total), the unit will remain in defrost
mode until the defrost thermostat opens or 14 minutes
have passed. If the jumper is not removed until after the
additional 5-second period has elapsed, the defrost will
terminate and the test option will not function again until the
jumper is removed and re-applied.
COMPRESSOR DELAY
The defrost board has a field-selectable function to reduce
occasional sounds that may occur while the unit is cycling
in and out of the defrost mode. The compressor will be
cycled off for 30 seconds going in and out of the defrost
mode when the compressor delay jumper is removed.
NOTE - The 30-second compressor feature is ignored
when jumpering the TEST pins.
TIME DELAY
The timed-off delay is five minutes long. The delay helps to
protect the compressor from short-cycling in case the
power to the unit is interrupted or a pressure switch opens.
The delay is bypassed by placing the timer select jumper
across the TEST pins for 0.5 seconds.
PRESSURE SWITCH CIRCUIT
The defrost control incorporates two pressure switch
circuits. The high pressure switch (S4) is
factory-connected to the board's HI PS terminals (see
figure 36). The board also includes a low pressure, or
loss-of-charge-pressure, switch (S87). Switches are
shown in wiring diagrams in figures 29 and 36.
During a single demand cycle, the defrost control will lock
out the unit after the fifth time that the circuit is interrupted
by any pressure switch wired to the control board. In
addition, the diagnostic LEDs will indicate a locked-out
pressure switch after the fifth occurrence of an open
pressure switch as listed in table 12. The unit will remain
locked out until power to the board is interrupted, then
re-established or until the jumper is applied to the TEST
pins for 0.5 seconds.
Table 12. Defrost Control Board Diagnostic LED
Mode Green LED (DS2) Red LED (DS1)
No power to con-
OFF OFF
trol
Normal operation / Simultaneous Slow FLASH
power to control
Anti-short cycle
lockout Alternating Slow FLASH
Low pressure OFF Slow FLASH
switch fault
Low pressure OFF ON
switch lockout
High pressure Slow FLASH OFF
switch fault
High pressure ON OFF
switch lockout
NOTE - The defrost control board ignores input from the
low-pressure switch terminals as follows:
• during the TESTmode,
• during the defrost cycle,
• during the 90-second start-up period,
• and for the first 90 seconds each time the reversing
valve switches heat/cool modes.
DIAGNOSTIC LEDS
The defrost board uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
WARNING
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.
• 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.)
• Visually inspect the refrigerant lines and coils for leaks.
• Check wiring for loose connections.
• Check voltage at the indoor and outdoor units (with
units operating).
• Check the amperage draw at the outdoor fan motor,
compressor, and indoor blower motor. Values should
be compared with those given on unit nameplate.
• Check, clean (or replace) indoor unit filters.
• Check the refrigerant charge and gauge the system
pressures.
• Check the condensate drain line for free and
unobstructed flow; clean, if necessary.
• 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.
• Check drive belt for wear and proper tension.
NOTE - If owner reports insufficient cooling, the unit
should be gauged and refrigerant charge checked.
Refer to section on refrigerant charging in this
instruction.
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