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NOTE - The 30-second "off" cycle is not functional 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 optional high pressure switch (S4) connects
to the board's HI PS terminals. The board also includes
connections
for
an
optional
low
pressure,
or
loss-of-charge-pressure,
switch
(S87),
Switches
are
shown in figure 22,
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 (see Table 8). 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,
NOTE - The defrost control board ignores input from the
low-pressure switch terminals as follows:
•
during the TEST mode,
•
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.
Table 8
Defrost
Control
Board Diagnostic
LED
Mode
Green LED (DS2)
Red LED (DS1)
No power to control
OFF
OFF
Normal
operation
/
Simultaneous Slow FLASH
power to control
Anti-short cycle lock-
out
Alternating Slow FLASH
Low pressure switch
OFF
Slow FLASH
fault
(Optional)
Low pressure switch
OFF
ON
lockout (Optional)
High pressure switch
Slow FLASH
OFF
fault
(Optional)
High pressure switch
ON
OFF
lockout (Optional)
_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.
NOTE - If owner reports insufficient cooling, the unit
should be gauged and refrigerant charge checked.
Refer
to
section
on refrigerant
charging in
this
instruction.
Refer
to
the
Engineering
Handbook
for
optional
accessories that may apply to this unit. The following may
or may not apply:
•
Loss of Charge Kit
•
High Pressure Switch Kit
•
Mild Weather Kit
•
Compressor Monitor
•
Compressor Crankcase Heater
•
Mounting Bases
•
Sound Cover
•
Low Ambient Kit
•
Monitor Kit
•
Dave Lennox Signature Stat'" Room Thermostat
505076M
0_07
Page 16
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