Filter
Top Products
28
Installation, Operation & Maintenance HTV/HTD/HTH SERIES Heat Controller, Inc.
CXM Controls
Safety Features – CXM Control
The safety features below are provided to protect the compressor,
heat exchangers, wiring and other components from damage
caused by operation outside of design conditions.
Anti-short cycle protection: The control features a 5 minute anti-
short cycle protection for the compressor.
Note: The 5 minute anti-short cycle also occurs at power up.
Random start: The control features a random start upon power up
of 5-80 seconds.
Fault Retry: In Fault Retry mode, the Status LED begins slowly
fl ashing to signal that the control is trying to recover from a fault
input. The control will stage off the outputs and then “try again”
to satisfy the thermostat input call. Once the thermostat input call
is satisfi ed, the control will continue on as if no fault occurred. If
3 consecutive faults occur without satisfying the thermostat input
call, the control will go into “lockout” mode. The last fault causing
the lockout will be stored in memory and can be viewed by going
into test mode. Note: FP1/FP2 faults are factory set at only one
try.
Lockout: In lockout mode, the status LED will begin fast fl ashing.
The compressor relay is turned off immediately. Lockout mode can
be “soft” reset by turning off the thermostat (or satisfying the call).
A “soft” reset keeps the fault in memory but resets the control. A
“hard” reset (disconnecting power to the control) resets the control
and erases fault memory.
Lockout with emergency heat: While in lockout mode, if W becomes
active (CXM), emergency heat mode will occur.
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 fl ashes, 10 sec pause, 2 quick fl ashes, 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 selected 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 120 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 120 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 overfl ow: The condensate overfl ow sensor must
sense overfl ow level for 30 continuous seconds to be recognized
as a CO fault. Condensate overfl ow 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 18VAC to
31.5VAC. 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 ineffi ciently. 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) I
n 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 fl ash Code 1 (when in test mode).