Carrier 38AU Installation, Start-up And Service Instructions Manual

Also see for 38AU: Installation, Start-Up and Service Instructions Installation, Start-Up and Service Instructions

Carrier 38AU Installation, Start-up And Service Instructions Manual Manual pdf 35 page image

35Comfort Alert Diagnostic ModuleThe Comfort Alert Diagnostic Module (CADM) monitorsand analyzes data from the Copeland Scroll® three-phasecompressor and the thermostat demand. The CADM alsoprovides a 3-minute anti-recycle time delay to compressorcycling. Each compressor has a separate CADM module.The CADM detects causes for electrical and systemrelated failures without any sensors. Flashing LEDscommunicate the Alert codes to guide service techniciansin accurately and quickly troubleshooting the system anddetermining root cause for the failure.Inputs to the CADM include 24-vac power, thermostat Y1or Y2, compressor contactor coil (common side) andcompressor power leads (from the compressor contactor).Input Terminal VoltageControlPower R 24-VControlCommon C 24-VCooling Y 24-VContactorCoil P 24-VLine A T1 LineLine B T2 LineLine C T3 LineControl of the compressor contactor coil is through anormally-closed (power on the module) contact betweenterminals P and C.Communications of status and alert conditions is throughthree LEDs located on the top edge of the module housing(see Fig. 32): POWER (green), ALERT (yellow), andTRIP (red).The POWER LED indicates the presence of control powerto the CADM.The ALERT LED indicates an abnormal condition existsin the system through a flash code. The ALERT LED willblink a number of times consecutively, pause and therepeat the process. The number of blinks, defined in Table11, correlates to a particular abnormal condition;troubleshooting tips are provided for each Alert code.Reset of the ALERT may be automatic or manual. If thefault condition causing the Alert is self-corrected, theAlert code will be removed and the CADM willautomatically reset and allow the system to restartnormally. Manual reset requires that main power to the38AU unit be recycled after the cause for the Alertcondition has been detected and corrected.POWER(GRN)ALERT(YEL)TRIP(RED)C10086Fig. 32 -- CADM Housing/LED LocationsThe TRIP LED indicates either a time-delay period iscurrently active (RED LED is blinking) or the module haslocked out the compressor (RED LED is on steady). Alockout condition will occur when the CADM detects athermostat demand at input Y but there is no power at thecompressor line terminals T1 or T2 or T3. This lockoutcan occur due to a safety switch (LPS or HPS) openingand de-energizing the compressor contactor, thecompressor-motor internal overload opens, or otherinternal power interruption has occurred. Reset of theTRIP LED requires that unit main power be recycled afterthe loss of power to the compressor condition has beendetected and corrected.Simultaneous Blinking of YELLOW and RED LEDsindicates control power input to the CADM is low. Checkcontrol circuit transformer and wiring.Troubleshooting the CADM Wiring – Flashing LEDs alsoindicate wiring problems to the CADM. See Table 12 fordiscussion of additional LED flash codes andtroubleshooting instructions.38AU