Maintenance (Dealer And Homeowner) - Lennox Merit 13HPX Series Installation Instructions Manual

NOTE Defrost control part number is listed near the P1
timing pins.
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Units with defrost control 100269−02: Factory default
is 60 minutes
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Units with defrost control 100269−04: Factory default
is 90 minutes
If the timing selector jumper is missing, the defrost
control defaults to a 90−minute defrost interval.
Compressor Delay (P5)
The defrost control has a field−selectable function to
reduce occasional sounds that may occur while the unit is
cycling in and out of the defrost mode.
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Units with defrost control 100269−02: The compressor
will be cycled off for 30 seconds going in and out of the
defrost mode when the compressor delay jumper is
removed.
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Units with defrost control 100269−04: The compressor
will be cycled off for 30 seconds going in and out of the
defrost mode when the compressor delay jumper is
installed.
NOTE The 30-second compressor feature is ignored
when jumpering the TEST pins.
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.
A TEST option is provided for troubleshooting. The TEST
mode may be started any time the unit is in the heating
mode and the defrost thermostat is closed or
jumpered. If the jumper is in the TEST position at
power-up, the defrost control will ignore the test pins.
When the jumper is placed across the TEST pins for two
seconds, the defrost control will enter the defrost mode. If
the jumper is 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.
Service Light Connection
The defrost control includes terminal connections for a
service light which provides a signal that activates the
room thermostat service light during periods of inefficient
operation.
Defrost Control Diagnostic LEDs
The defrost board uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
506727−01
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Time Delay
Test Mode (P1)
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Table 6. Defrost Control (CMC1) Diagnostic LEDs
Mode
No power to con-
trol
Normal operation /
power to control
Anti-short cycle
lockout
High pressure
switch fault
High pressure
switch lockout
Maintenance
1. Clean and inspect outdoor coil (may be flushed with a
water hose). Ensure power is off before cleaning.
2. Outdoor unit fan motor is pre−lubricated and sealed.
No further lubrication is needed.
3. Visually inspect all connecting lines, joints and coils for
evidence of oil leaks.
4. Check all wiring for loose connections.
5. Check for correct voltage at unit (unit operating).
6. Check amp draw on outdoor fan motor.
Motor Nameplate:_________ Actual:__________.
7. Inspect drain holes in coil compartment base and
clean if necessary.
NOTE - If insufficient heating or cooling occurs, the unit
should be gauged and refrigerant charge should be
checked.
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, fertilizers, fluids that may contain
high levels of corrosive chemicals such as salts)
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Outdoor Coil
a water hose.
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Outdoor Coil (Sea Coast)
locations can carry salt, which is corrosive to most
metal. Units that are located near the ocean require
frequent inspections and maintenance. These
inspections will determine the necessary need to wash
the unit including the outdoor coil. Consult your
installing contractor for proper intervals/procedures
for your geographic area or service contract.
1. Clean or change filters.
2. Lennox blower
permanently sealed. No more lubrication is needed.
3. 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.
4. Belt Drive Blowers − Check belt for wear and proper
tension.
Page 30
Green LED (DS2) Red LED (DS1)
OFF OFF
Simultaneous Slow FLASH
Alternating Slow FLASH
Slow FLASH OFF
ON OFF
Outdoor Unit
Outdoor Coil
The outdoor coil may be flushed with
Moist air in ocean
Indoor Unit
motors are prelubricated and