9
TROUBLESHOOTING
SYSTEMS COMMUNICATION FAILURE
If communication between outdoor unit, control board, and indoor
user interface control has failed, the control will flash the
appropriate fault code. (See table 3) Check the wiring to the UI,
indoor and outdoor units.
PRESSURE SWITCH PROTECTION
The outdoor unit is equipped with high-- and low--pressure
switch es. If th e co n tro l sen ses th e o p en in g o f a h ig h o r
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 for airflow restrictions.
In the event of a low--pressure switch trip or low--pressure lockout,
check the refrigerant charge and indoor airflow.
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. 11) 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
If the compressor voltage is not sensed when the 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).
If the outdoor air or coil thermistor should fail, the control will
flash the appropriate fault code. (See table 3)
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 (
≥
--12.22
_
C) warmer than the coil sensor
(or) the outdoor air sensor indicates
≥
20
_
F (
≥
--6.67
_
C) 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 OPERA-
TION
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
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
60
_
F (15.56
_
C), 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.
24AN
B
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