Bryant Preferred 163A Installation Instructions Manual page 12

IMPORTANT: The outdoor air thermistor and coil thermistor
are factory mounted in the correct locations. Do not re- -locate
thermistor sensors.
THERMISTOR SENSOR COMPARISON
The control continuously monitors and compares the outdoor air
temperature sensor and outdoor coil temperature sensor to ensure
proper operating conditions. The comparison is, if the outdoor air
sensor indicates ≥10 _F warmer than the coil sensor (or) the
outdoor air sensor indicates ≥20_F cooler than the coil sensor, the
sensors are out of range.
If the sensors are out of range, the control will flash the
appropriate fault code. (See Table 3)
The thermistor comparison is not performed during low ambient
cooling.
FAILED THERMISTOR DEFAULT OPERATION
Factory defaults have been provided in the event of failure of
outdoor air thermistor and/or coil thermistor.
If the OAT sensor should fail, low ambient cooling will not be
allowed, and the one minute outdoor fan off delay will not occur.
If the OCT sensor should fail, low ambient cooling will not be
allowed.
Thermistor Curve: The resistance vs. temperature chart shown in
Figure 12 enables the technician to check the outdoor air and
OPERATION FAULT
Standby – no
call for unit None
operation
Standby – no
call for unit None
operation
Cooling
None
Operation
System
Communications
Failure
High Pressure Switch
Open
Low Pressure Switch
Open
Control Fault
Brown Out
(24 v)
Outdoor Air Temp
Sensor Fault
Outdoor Coil Sensor
Fault
Thermistors out of
range
Thermal Cutout
Contactor Shorted
No 230V at Compres-
sor
Thermal Lockout
Low Pressure Lockout
High Pressure Lock-
out
outdoor coil thermistors for proper resistance. Unplug the
thermistor assembly from the circuit board and measure resistance
across each thermistor. For example, if the outdoor temperature is
60ºF, the resistance reading across the outdoor air thermistor
should be around 16,000 Ohms.
STATUS CODES
Table 3 shows the status codes flashed by the amber status light.
Most system problems can be diagnosed by reading the status
code as flashed by the amber status light on the control board.
The codes are flashed by a series of short and long flashes of the
status light. The short flashes indicate the first digit in the status
code, followed by long flashes indicating the second digit of the
error code. The short flash is 0.25 second ON and the long flash
is 1.0 second ON. Time between flashes is 0.25 second. Time
between short flash and first long flash is 1.0 second. Time
between code repeating is 2.5 seconds with LED OFF.
Count the number of short and long flashes to determine the
appropriate flash code. Table 3 gives possible causes and actions
related to each error.
Example: 3 short flashes followed by 2 long flashes indicates a
32 code. Table 3 shows this to be low pressure switch open.
Table 3— Status Codes
AMBER LED
FLASH CODE
On solid, no flash Normal operation --- 3 thermostat wires or 4 wire Evolution Control
Normal operation --- No call for cooling with 2--- wire connection or indoor
Off
unit not powered.
1, pause
Normal operation
16 Communication with user interface lost. Check wiring to UI, indoor and
outdoor units
High pressure switch trip. Check refrigerant charge, outdoor fan opera-
31
tion and coils for airflow restrictions.
32
Low pressure switch trip. Check refrigerant charge and indoor air flow
Outdoor unit control board has failed. Control board needs to be re-
45
placed.
The control voltage is less than 15.5v for at least 4 seconds. Compressor
46 and fan operation not allowed until control voltage is a minimum of 17.5v.
Verify control voltage.
53 Outdoor air sensor not reading or out of range. Ohm out sensor and
check wiring
55
Coil sensor not reading or out of range. Ohm out sensor and check wiring
56 Improper relationship between coil sensor and outdoor air sensor. Ohm
out sensors and check wiring.
Compressor voltage sensed after start--- up, then absent for 10 consecu-
tive seconds while cooling demand exists. Possible causes are internal
compressor overload trip or loss of high voltage to compressor without
72
loss of control voltage. The control will continue fan operation and wait
15 minutes to attempt a restart. Fault will clear when restart is successful,
or low voltage power is cycled.
73 Compressor voltage sensed when no demand for compressor operation
exists. Contactor may be stuck closed or there is a wiring error.
Compressor voltage not sensed when compressor should be starting.
74 Disconnect may be open or contactor may be stuck open or there is a
wiring error.
82 Thermal cutout occurs in three consecutive cycles. Unit operation locked
out for 4 hours or until 24v power recycled.
Low pressure switch trip has occurred during 5 consecutive cycles. Unit
83
operation locked out for 4 hours or until 24v power recycled.
High pressure switch trip has occurred during 5 consecutive cycles. Unit
84
operation locked out for 4 hours or until 24v power recycled.
12
Possible Cause and Action