Major Components; Troubleshooting; Field Connections - Carrier Infinity 25HNB5 Installation Instructions Manual

is de–energized for 70 seconds. During this 70 second compressor
off time, the reversing valve will be energized. Once the 70 second
compressor off time has been reached, the compressor will be
energized then the outdoor fan will be de–energized at which time
the normal defrost cycle begins. Defrost Termination – the
outdoor fan will be energized shortly before the compressor is
de–energized for 60 seconds. During the compressor 60 second off
time, the reversing valve will be de–energized. Once the 60 second
compressor off time has been completed, the compressor will be
energized at which time the system will be in normal heat mode.
LIQUID LINE SOLENOID ACCESSORY
In heat pump long line applications, a liquid line solenoid is
required to control refrigerant migration in the heating mode. The
solenoid should be installed near the outdoor unit with the arrow
facing the outdoor unit. This is the direction of flow control. See
Long Line Application Guideline for details.
Accessory Liquid Solenoid with Infinity Communicating Control:
When using the Infinity Control, a liquid line solenoid output
labeled LS is provided. Connect the solenoid as shown in the
wiring label diagram. This is a 24vac output that is energized
whenever the compressor is energized. It closes in the
compressor–off mode to prevent refrigerant migration into the unit
through the liquid line.
Accessory Liquid Solenoid
Thermostat: The liquid solenoid is connected to the Y and C
terminal connections. The liquid solenoid closes in the
compressor–off mode to prevent refrigerant migration into the unit
through the liquid line.

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 Infinity communicating control, 4 field wires are
required to be connected to the factory wires already wired to the
ABCD terminal (see Fig. 12). Unit as provided by manufacturer is
set up for Infinity communicating control.
When used with a standard non–communicating thermostat,5 field
wires are required to be connected to R, Y, W2, O and C.
Disconnect factory provided wires from A, B, C, and D 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 cap both
sides or remove unused factory provided wires.
On Infinity 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 ABCD
Infinity 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 psig. The compressor is also protected by an internal
overload attached to motor windings.
with Non–Communicating

TROUBLESHOOTING

Systems Communication Failure
If communication between User Interface (UI), and condensing
unit is lost, the outdoor control will flash the appropriate fault
code. (See Table 4) Check the wiring to the UI, 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 4)
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 4) 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 (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 4) 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 4) 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. 12) 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 4) 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.
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.
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If the call for cooling