Comfort-Aire HKV300A - Manual (Page 23)

Installation, Operation & Maintenance HKV SERIES Heat Controller, LLC
22
Safety Features
Safety Features – CXM Control
The safety features below are provided to protect the compres-
sor, 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
ÀDVKLQJWRVLJQDOWKDWWKHFRQWUROLVWU\LQJWRUHFRYHUIURPDIDXOW
input. The control will stage off the outputs and then “try again”
to satisfy the thermostat input call. Once the thermostat input call
LVVDWLV¿HGWKHFRQWUROZLOOFRQWLQXHRQDVLIQRIDXOWRFFXUUHG,I
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 (CXM board). Note: FP1/FP2 faults are factory set
at only one try.
Lockout ,QORFNRXWPRGHWKHVWDWXV/('ZLOOEHJLQIDVWÀDVKLQJ
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 con-
trol. 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 be-
comes 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-ener-
gized 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
([DPSOH TXLFNÀDVKHVVHFSDXVHTXLFNÀDVKHVVHF
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 120 seconds of a compres-
sor run cycle.
Low pressure lockout code = 3
Water coil low temperature (FP1): The FP1 thermistor tempera-
ture must be below the selected low temperature limit setting for
30 continuous seconds during a compressor run cycle to be rec-
ognized 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 recog-
nized 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
&RQGHQVDWHRYHUÀRZ 7KHFRQGHQVDWHRYHUÀRZVHQVRUPXVW
VHQVHRYHUÀRZOHYHOIRUFRQWLQXRXVVHFRQGVWREHUHFRJQL]HG
DVD&2IDXOW&RQGHQVDWHRYHUÀRZZLOOEHPRQLWRUHGDWDOOWLPHV
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, nor-
mal 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 fea-
WXUHLQGLFDWHVZKHQWKHKHDWSXPSLVRSHUDWLQJLQHI¿FLHQWO\$836
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 nor-
mal 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 re-
lay 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 appro-
priate 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 sen-
sor is colder than the FP2 sensor, or:
b) The compressor is on in the heating mode and the FP2 sen-
sor 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
IDXOWLQPHPRU\WKH/('ZLOOÀDVK&RGH ZKHQLQWHVWPRGH 
CXM 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
PLQXWHDQWLVKRUWF\FOHGHOD\DWSRZHUXS7KH¿UVWWLPHDIWHU
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.