23
High pressure switch: When the high pressure switch opens
due to high refrigerant pressures, the compressor relay is
de-energized immediately since the high pressure switch
is in series with the compressor contactor coil. The high
pressure fault recognition is immediate (does not delay for 30
continuous seconds before de-energizing the compressor).
High pressure lockout code = 2
Example: 2 quick flashes, 10 sec pause, 2 quick flashes,
10 sec. pause, etc.
Low pressure switch: The low pressure switch must be open
and remain open for 30 continuous seconds during “on”
cycle to be recognized as a low pressure fault. If the low
pressure switch is open for 30 seconds prior to compressor
power up it will be considered a low pressure (loss of
charge) fault. The low pressure switch input is bypassed for
the initial 60 seconds of a compressor run cycle.
Low pressure lockout code = 3
Water coil low temperature (FP1): The FP1 thermistor
temperature must be below the 30˚F low temperature
limit setting for 30 continuous seconds during a
compressor run cycle to be recognized as a FP1 fault.
The FP1 input is bypassed for the initial 60 seconds of a
compressor run cycle. FP1 is set at the factory for one try.
Therefore, the control will go into lockout mode once the
FP1 fault has occurred.
FP1 lockout code = 4
Air coil low temperature (FP2): The FP2 thermistor
temperature must be below the selected low temperature
limit setting for 30 continuous seconds during a
compressor run cycle to be recognized as a FP2 fault.
The FP2 input is bypassed for the initial 60 seconds of a
compressor run cycle. FP2 is set at the factory for one try.
Therefore, the control will go into lockout mode once the
FP2 fault has occurred.
FP2 lockout code = 5
Condensate overflow: The condensate overflow sensor
must sense overflow level for 30 continuous seconds to
be recognized as a CO fault. Condensate overflow will be
monitored at all times.
CO lockout code = 6
Over/under voltage shutdown: An over/under voltage
condition exists when the control voltage is outside the
range of 19VAC to 30VAC. Over/under voltage shut
down is a self-resetting safety. If the voltage comes back
within range for at least 0.5 seconds, normal operation is
restored. This is not considered a fault or lockout. If the
CXM is in over/under voltage shutdown for 15 minutes,
the alarm relay will close.
Over/under voltage shut down code = 7
Unit Performance Sentinel-UPS (patent pending): The
UPS feature indicates when the heat pump is operating
inefficiently. A UPS condition exists when:
a) In heating mode with compressor energized, FP2 is
greater than 125°F [52°C] for 30 continuous seconds,
or:
b) In cooling mode with compressor energized, FP1 is
greater than 125°F [52°C] for 30 continuous seconds,
or:
c) In cooling mode with compressor energized, FP2 is
less than 40°F [4.5°C] for 30 continuous seconds.
If a UPS condition occurs, the control will immediately
go to UPS warning. The status LED will remain on as
if the control is in normal mode. Outputs of the control,
excluding LED and alarm relay, will NOT be affected
by UPS. The UPS condition cannot occur during a
compressor off cycle. During UPS warning, the alarm
relay will cycle on and off. The cycle rate will be “on” for 5
seconds, “off” for 25 seconds, “on” for 5 seconds, “off” for
25 seconds, etc.
UPS warning code = 8
Swapped FP1/FP2 thermistors: During test mode, the
control monitors to see if the FP1 and FP2 thermistors
are in the appropriate places. If the control is in test
mode, the control will lockout with code 9 after 30
seconds if:
a) The compressor is on in the cooling mode and the
FP1 sensor is colder than the FP2 sensor, or:
b) The compressor is on in the heating mode and the
FP2 sensor is colder than the FP1 sensor.
Swapped FP1/FP2 thermistor code = 9.
Diagnostic Features
The LED on the CXM board advises the technician of the
current status of the CXM control. The LED can display
either the current CXM mode or the last fault in memory
if in test mode. If there is no fault in memory, the LED will
flash Code 1 (when in test mode).
Control Start-up Operation
The control will not operate until all inputs and safety
controls are checked for normal conditions. The
compressor will have a 5 minute anti-short cycle delay
at power-up. The first time after power-up that there is a
call for compressor, the compressor will follow a 5 to 80
second random start delay. After the random start delay
and anti-short cycle delay, the compressor relay will
be energized. On all subsequent compressor calls, the
random start delay is omitted.
SAFETY FEATURES - CXM CONTROLS
CXM CONTROL
To Next Page
Loading...
