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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
3)
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 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 (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. 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 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).
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)
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
•
In cooling
if
the
outdoor
air
sensor
indicates
.>
10 ° F/-12.22
° C warmer
than the coil sensor (or) the out-
door air sensor indicates
->20 ° F/-6.67
°C cooler
than the
coil sensor,
the sensors
are out of range.
•
In
heating
if
the
outdoor
air
sensor
indicates
->35°F/1.67°C
warmer
than the coil sensor (or) the out-
door air sensor
indicates
->10°F/-12.22°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
or defrost
operation.
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.
Defrost will be initiated based on coil temperature
and time.
If the OCT sensor
should
fail, low ambient
cooling
will not be
allowed.
Defrost
will occur
at each time interval
during
heating
operation,
but will terminate
after 5 minutes.
If there is a thermistor
out of range
error,
defrost
will occur
at
each time interval
during
heating
operation,
but will terminate
after 5 minutes.
Thermistor
Curve:
The resistance
vs. temperature
chart shown
in Fig. 14 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.
10
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