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INSTALLATION INSTRUCTIONS
MAJOR COMPONENTS
Control Board
The Heat Pump control board controls the following
functions:
S Compressor contactor operation
S Outdoor fan motor operation
S Reversing valve operation
S Defrost operation
S Compressor external protection
S Pressure switch monitoring
S Time delays
Field Connections
When using the Observer Communicating Wall Control, 4
field wires are required to be connected to the factory wires
already wired to the DX+DX- CR terminal (see Fig. 12). Unit
as provided by manufacturer is set up for the Observer
Communicating Wall Control.
W h e n u s e d w i t h a s t a n d a r d n o n - c o m m u n i c a t i n g
thermostat,5 field wires are required to be connected to R, Y,
W2, O and C. Disconnect factory provided wires from DX+,
DX- , C, and R terminals. Using factory provided wires,
connect to R, Y, W2, O and C terminals on the control board.
Connect field 24V wires to factory provided wires now
connected to R, Y, W2, O and C and unused factory provided
wires.
When using Observer communication wall control only, the
24vac LS (liquid solenoid) output terminal is energized for the
liquid solenoid accessory. The connection is located at the
side of the control board just below the DX+DX - CR
connector.
Compressor Internal Relief
The compressor is protected by an internal pressure relief
(IPR) which relieves discharge gas into the compressor shell
when differential between suction and discharge pressure
exceeds 550- 625 psi. The compressor is also protected by
an internal overload attached to motor windings.
TROUBLESHOOTING
SYSTEMS COMMUNICATION FAILURE
If communication between Wall Control, and condensing unit
is lost, the outdoor control will flash the appropriate fault
code. (See Table 3) Check the wiring to the Wall Control,
indoor and outdoor units.
PRESSURE SWITCH PROTECTION
The outdoor unit is equipped with high- and low- pressure
switches. If the control senses the opening of a high or
low- pressure switch, it will de- energize the compressor
contactor, keep the outdoor fan operating for 15 minutes and
display the appropriate fault code. (See table 3)
After a 15 minute delay, if there is still a call for cooling, and
the LPS or HPS is reset, the compressor contactor is
energized. If the LPS or HPS has not closed after a 15
minute delay, the outdoor fan is turned off. If the open switch
closes anytime after the 15- minute delay, then the unit will
resume operation with a call for cooling.
If the LPS or HPS trips for five consecutive cycles, then unit
operation is locked out for 4 hours and the appropriate fault
code (See table 3) is displayed.
In the event of a high- pressure switch trip or high- pressure
lockout, check the refrigerant charge, outdoor fan operation
and outdoor coil (in cooling) for airflow restrictions, or indoor
airflow in heating.
In the event of a low- pressure switch trip or low- pressure
lockout, check the refrigerant charge and indoor airflow
428 01 5400 00
(cooling) and outdoor fan operation and outdoor coil in
heating.
CONTROL FAULT
If the outdoor unit control board has failed, the control will
flash the appropriate fault code. (See table 3) The control
board should be replaced.
24V BROWN OUT PROTECTION
If the control voltage is less than 15.5volts for at least 4
seconds, the compressor contactor and fan relay are
de- energized. Compressor and fan operation are not
allowed until control voltage is a minimum of 17.5volts. The
control will flash the appropriate fault code. (See table 3)
Verify the control voltage is in the allowable range of
18- 30volts.
COMPRESSOR VOLTAGE SENSING
The input terminals labeled VR and VS on the control board
(see Fig. 13) are used to detect compressor voltage status,
and alert the user of potential problems. The control
continuously monitors the high voltage on the run capacitor
of the compressor motor. Voltage should be present any time
the compressor contactor is energized, and voltage should
not be present when the contactor is de- energized.
COMPRESSOR THERMAL CUTOUT OR LOSS OF
230V POWER
If the control senses the compressor voltage after start- up,
and is then absent for 10 consecutive seconds while cooling
demand exists, it will de- energize the compressor contactor,
keep the outdoor fan operating for 15 minutes (if 230v power
present) and display the appropriate fault code. (See table 3)
Possible causes are compressor internal overload trip or loss
of high voltage (230V) to compressor without loss of control
voltage.
After a 15 minute delay, if there is still a call for cooling, the
compressor contactor is energized. If the thermal protector
has not re- set, the outdoor fan is turned off. If the call for
cooling continues, the control will energize the compressor
contactor every 15 minutes. If the thermal protector closes,
(at the next 15 minute interval check), the unit will resume
operation.
If the thermal cutout trips for three consecutive cycles, then
unit operation is locked out for 4 hours and the appropriate
fault code (See Table 3) is displayed.
CONTACTOR SHORTED DETECTION
If there is compressor voltage sensed when there is no
demand for compressor operation, the contactor may be
stuck closed. The control will flash the appropriate fault
code. Check the contactor and control box wiring.
NO 230V AT COMPRESSOR
I f t h e c o m p r e s s o r v o l t a g e i s n o t s e n s e d w h e n t h e
compressor should be starting, the contactor may be stuck
open or the unit disconnect or circuit breaker may be open.
The control will flash the appropriate fault code. Check the
contactor, unit disconnect or circuit breaker and control box
wiring.
TEMPERATURE THERMISTORS
Thermistors are electronic devices which sense temperature.
As the temperature increases, the resistance decreases.
Thermistors are used to sense outdoor air (OAT) and coil
temperature (OCT). Refer to Fig. 14 for resistance values
versus temperature.
If the outdoor air or coil thermistor should fail, the control will
flash the appropriate fault code. (See table 3).
Specifications subject to change without notice.
R- 410A Split System Heat Pumps
11
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