JRC-Series
R e v. : D e c e m b e r 8 , 2 0 2 1
T H E S M A R T S O L U T I O N F O R E N E R G Y E F F I C I E N C Y
I n s t a l l a t i o n , O p e r a t i o n , M a i n t e n a n c e
29
Safety Features – CXM/DXM Controls, Cont’d.
Unit Performance-UPS:
The UPS feature indicates when
the heat pump is operating inefficiently. A UPS condition
exists when:
a. In heating mode with compressor energized, LT2 is
greater than 125°F [52°C] for 30 continuous seconds,
or:
b. In cooling mode with compressor energized, LT1 is
greater than 125°F [52°C] for 30 continuous seconds,
or:
c. In cooling mode with compressor energized, LT2 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, exclud-
ing 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 LT1/LT2 thermistors:
During test mode, the
control monitors to see if the LT1 and LT2 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 LT1
sensor is colder than the LT2 sensor, or:
b. The compressor is on in the heating mode and the
LT2 sensor is colder than the LT1 sensor.
Swapped LT1/LT2 thermistor code = 9.
ESD (DXM only):
The ESD (Emergency Shut Down) mode
can be enabled from an external common signal to termi-
nal ESD to shut down the unit. The green status light will
flash code 3 when the unit is in ESD mode.
ESD mode = code 3 (green “status” LED)
CXM/DXM CONTROLS
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).
The green status LED and red fault LED on the DXM
board advise the technician of the current status of the
DXM control. The status LED will indicate the current
mode that the DXM control is in. The fault LED will
ALWAYS flash a code representing the LAST fault in
memory. If there is no fault in memory, the fault LED will
flash Code 1. The yellow test LED will turn on when in
test mode.
CAUTION: Do not restart units without
inspection and remedy of faulting condition. Damage
may occur.
CXM/DXM 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.
