Model Plug; Pressure Switch Protection; Brown-Out Protection; Compressor Voltage Sensing - Carrier 25HNA6 Installation Instruction

500-550 psion25HNA6 models and 550-625 psion25HNA9
models. The compressor isalso protected byaninternal overload
attached tomotor windings.
Compressor Control Contactors
The contactor(s) have a 24volt coil. The electronic control board
controls the operation of the appropriate contactor.
TROUBLESHOOTING
Systems Communication Failure
If conmmnication with the Infinity control is lost with the User
Interface, the control will flash the @propriate fault code. (See
Table 6.) Check the wiring to the UI and the indoor and outdoor
units.
Model Plu_
Each control board contains a model plug. The correct model plug
must be installed for or the system to operate properly. (See Table
4.)
Table 4 - Model Plug Information
MODEL
NUMBER
MODEL
PLUG
NUMBER
PIN RESISTANCE
(K-ohms)
Pins 1-4
5.1
5.1
5.1
5.1
25 H NA624 HK70 EZO02
25 H NA636 HK70 EZO04
25 H NA648 HK70 EZO06
25 H NA660 HK70 EZO08
25H NA924 HK7OEZ010 5.1 120
25H NA936 HK7OEZ012 5.1 180
25H NA948 HK7OEZ014 5.1 270
25H NA960 HK7OEZ016 11 5.1
Pins 2-3
18
33
51
75
The model plug is used to identify the type and size of unit to the
control. On 25HNA6 models, the model plug is also used to
determine the start sequence timing for each individual model.
On new units, the model and serial numbers are input into the
board's memory at the factory. If a model plug is lost or missing at
initial installation, the unit will operate according to the
information input at the factory and the appropriate error code will
flash temporarily. An RCD replacement board contains no model
and serial information. If the factory control board fails, the model
plug must be transferred from the original board to the replacement
board for the unit to operate.
NOTE: The model plug takes priority over factory model
information input at the factory. If the model plug is removed after
initial power up, the unit will operate according to the last valid
model plug installed, and flash the appropriate fault code
temporarily.
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 respond as follows:
1. De-energize the appropriate compressor contactor.
2. Keep the outdoor fan operating for 15 minutes.
3. Display the appropriate fault code (see Table 6).
4. After a 15 minute delay, if there is a call for cooling or heat-
ing and LPS or HPS is reset, the appropriate compressor
contactor is energized.
5. If 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 resume operation with a call
for cooling or heating.
6. If LPS or HPS trips 3 consecutive cycles, the unit operation
is locked out for 4 hours.
7. 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 in-
door airflow in heating.
8. 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 6). The control board should
be replaced.
Brown- Out Protection
If the line voltage is less than 187v for at least 4 seconds, the
appropriate compressor contactor and fan relay are de-energized.
Compressor and fan operation are not allowed until voltage is a
n_ininmm of 190v. The control will flash the appropriate fault code
(see Table 6).
230V Line (Power Disconnect) Detection
If there is no 230v at the compressor contactor(s) when the indoor
unit is powered and cooling or heating demand exists, the
appropriate fault code is displayed. Verify the disconnect is closed
and 230v wiring is connected to the unit.
Compressor Voltage Sensing
The control board input terminals labeled VS, VR and L2 on
25HNA6 models and VS and L2 on 25HNA9 models (see Fig. 6)
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.
Contactor Shorted Detection
If there is compressor voltage sensed when there is no demand for
compressor operation, the contactor may be stuck closed or there
may be a wiring error. The control will flash the appropriate fault
code.
25HNA6 Models - Compressor Thermal Cutout
The control senses the compressor voltage at VR and VS. When
starting or running, a phase difference of the voltages on the inputs
will indicate the thermal protector is closed. If the phase difference
is 5 ° or less for 10 seconds, the internal protector is open. The
control de-energizes the appropriate compressor contactor for 15
minutes, but continues to operate the outdoor fan. The control
Status LED will flash the appropriate code shown in Table 6. After
15 minutes, with a call for low or high stage cooling or heating, the
appropriate compressor contactor is energized. If the thermal
protector has not re-set, the outdoor fan is turned off. If the call for
cooling or heating 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 is
displayed.
25HNA9 Compressor Thermal Cutout
If the control senses the compressor voltage after start-up and is
then absent for 10 consecutive seconds while cooling or heating
demand exists, the thermal protector is open. The control
de-energizes the compressor contactor for 15 minutes, but
continues to operate the outdoor fan. The control Status LED will
flash the appropriate code shown in Table 6. After 15 minutes,
with a call for low or high stage cooling or heating, the compressor
contactor is energized. If the thermal protector has not re-set, the
outdoor fan is turned off. If the call for cooling or heating
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