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506728−01
Pressure Switch Circuit
The defrost control incorporates two pressure switch
circuits. The high pressure switch (S4) is
factory-connected to the defrost control’s HI PS terminals
(see figure 24). The defrost control also includes a low
pressure, or loss-of-charge-pressure, switch (S87).
Switches are shown in wiring diagrams in figure 15.
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 defrost control. 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 6. The unit will remain
locked out until power to the defrost control is interrupted,
then re-established or until the jumper is applied to the
TEST pins for 0.5 seconds.
Defrost Control Diagnostic LEDs
The defrost control uses two LEDs for diagnostics. The
LEDs flash a specific sequence according to the condition.
Table 6. Defrost Control (CMC1) Diagnostic LED
Mode
Green LED
(DS2)
Red LED (DS1)
No power to control OFF OFF
Normal operation / power
to control
Simultaneous Slow FLASH
Anti-short cycle lockout Alternating Slow FLASH
Low pressure switch fault OFF Slow FLASH
Low pressure switch
lockout
OFF ON
High pressure switch fault Slow FLASH OFF
High pressure switch
lockout
ON OFF
NOTE Ċ The defrost control ignores input from the
low-pressure switch terminals as follows:
S during the TEST mode,
S during the defrost cycle,
S during the 90-second start-up period,
S and for the first 90 seconds each time the reversing
valve switches heat/cool modes.
Maintenance
DEALER
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:
Outdoor Unit
1. Clean and inspect the outdoor coil. The coil may be
flushed with a water hose. Ensure the power is turned
off before you clean the coil.
2. Outdoor fan motor is prelubricated and sealed. No
further lubrication is needed.
3. Visually inspect connecting lines and coils for
evidence of oil leaks.
4. Check wiring for loose connections.
5. Check for correct voltage at the unit (with the unit
operating).
6. Check amp−draw outdoor fan motor.
UNIT NAMEPLATE: _________ ACTUAL: __________
NOTE Ċ If owner reports insufficient cooling, the unit
should be gauged and refrigerant charge checked.
Outdoor Coil
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)
S Outdoor Coil Ċ The outdoor coil may be flushed with
a water hose.
S Outdoor Coil (Sea Coast) Ċ Moist air in ocean
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.
Indoor Unit
1. Clean or change filters.
2. 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.
3. Check blower drive belt for wear and proper tension.
4. Check all wiring for loose connections
5. Check for correct voltage at unit (blower operating).
6. Check amp−draw on blower motor.
UNIT NAMEPLATE: _________ ACTUAL: __________
Indoor Coil
1. Clean coil, if necessary.
2. Check connecting lines and coils for signs of oil leaks.
3. Check condensate line and clean, if necessary.
NOTE Ċ The filter and all access panels must be in place
any time the unit is in operation.
HOMEOWNER
Cleaning of the outdoor unit’s coil should be performed by
a trained service technician. Contact your dealer and set
up a schedule (preferably twice a year, but at least once a
year) to inspect and service your outdoor unit. The
following maintenance may be performed by the
homeowner.
IMPORTANT
Sprinklers and soaker hoses should not be installed
where they could cause prolonged exposure to the
outdoor unit by treated water. Prolonged exposure of the
unit to treated water (i.e., sprinkler systems, soakers,
waste water, etc.) will corrode the surface of steel and
aluminum parts and diminish performance and longevity
of the unit.