Carrier 38AUM Series Installation, Operation & Maintenance Manual page 24

Comfort Alert Diagnostic Module
The Comfort Alert Diagnostic Module (CADM) monitors and analyzes data from the Copeland Scroll® three-phase
compressor and the thermostat demand. The CADM also provides a 3-minute anti-recycle time delay to compressor
cycling. Each compressor has a separate CADM module.
The CADM detects causes for electrical and system related failures without any sensors. Flashing LEDs communicate
the Alert codes to guide service technicians in accurately and quickly troubleshooting the system and determining root
cause for the failure.
Inputs to the CADM include 24-vac power, thermostat Y1 or Y2, compressor contactor coil (common side) and
compressor power leads (from the compressor contactor).
Control of the compressor contactor coil is through a normally-closed (power on the module) contact between
terminals P and C.
Communications of status and alert conditions is through three LEDs located on the top edge of the module housing
(see Fig:- CADM Housing/LED Locations): POWER (green), ALERT (yellow), and TRIP (red).
The POWER LED indicates the presence of control power to the CADM.
The ALERT LED indicates an abnormal condition exists in the system through a flash code. The ALERT LED will
blink a number of times consecutively, pause and the repeat the process. The number of blinks, defined in Table
LED Status Codes, correlates to a particular abnormal condition; troubleshooting tips are provided for each Alert code.
Reset of the ALERT may be automatic or manual. If the fault condition causing the Alert is self-corrected, the Alert
code will be removed and the CADM will automatically reset and allow the system to restart normally. Manual reset
requires that main power to the 38AU unit be recycled after the cause for the Alert condition has been detected and
corrected.
The TRIP LED indicates either a time-delay period is currently active (RED LED is blinking) or the module has locked
out the compressor (RED LED is on steady). A lockout condition will occur when the CADM detects a thermostat
demand at input Y but there is no power at the compressor line terminals T1 or T2 or T3. This lockout can occur due
to a safety switch (LPS or HPS) opening and de-energizing the compressor contactor, the compressor-motor internal
overload opens, or other internal power interruption has occurred. Reset of the TRIP LED requires that unit main
power be recycled after the loss of power to the compressor condition has been detected and corrected.
Simultaneous Blinking of YELLOW and RED LEDs indicates control power input to the CADM is low. Check control
circuit transformer and wiring.
Troubleshooting the CADM Wiring – Flashing LEDs also indicate wiring problems to the CADM. See Table – CADM
Troubleshooting for discussion of additional LED flash codes and troubleshooting instructions.
Input Terminal
Control Power
Control Common
Cooling
Contactor Coil
Line A T1
Line B T2
Line C T3
Fig:- CADM Housing/LED Locations
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Voltage
R 24-V
C 24-V
Y 24-V
P 24-V
Line
Line
Line