Carrier 48HC 04-28 Controls, Start-up, Operation And Troubleshooting

Also see for /50HC 04-28: Manual

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Carrier 48HC 04-28 Controls, Start-up, Operation And Troubleshooting Manual pdf 52 page image

52Economizer TroubleshootingUse the unit scrolling marquee display or a CCN device toview the economizer status display and the economizer diag-nostic display (see Appendix A) for information on the econo-mizer operation. Check the current alarms and alarm historyfor any economizer alarm codes and correct any causes. (SeeTable 14.) Verify any unique control configurations per in-stalled site requirements or accessories. If alarms conditionsare corrected and cleared, operation of the economizer may beverified by using the Service Test mode (see Service Test sec-tion and Table 6). The following steps specify how to test theeconomizer using the scrolling marquee display. See Table 18for general economizer service analysis.1. Enter the Service Test main menu on the display.2. Enter TEST and turn ON test mode. A password may beneeded in order to turn ON the Service Test. The defaultpassword is 1111.3. Return to the main level of Service Test.4. Enter the INDP submenu and enter an initial value forECON. This will drive the economizer damper to the spec-ified position. Continue to adjust the ECON value to makesure the economizer opens and closes.5. Because of a mechanical problem with the economizer, theactuator might acquire a new degree of rotation which isless than M.ANG. If this occurs, a “T414 EconomizerDamper Actuator Out of Calibration” alert will be gener-ated. This alert can only occur if the economizer is usingdigital communications (ConfigurationECONE.CTL= 1 or 2). The economizer calibration procedure (ServiceTestIND.PE.CAL) will reconfigure the actuator tothe new fully closed and fully open positions. To imple-ment the calibration procedure, change E.CAL from OFFto ON. E.CAL will remain ON as long as the calibrationprocedure is being implemented (as long as 5 minutes).During the calibration procedure the actuator will closefully and then open fully. After the calibration is complete,the degree of rotation should be greater than M.ANG,causing the T414 alert to clear. If the T414 alert does notclear, check the economizer damper for other mechanicalproblems.6. Return to Service TestTEST and turn OFF test mode.This will cause the unit to return to normal operation.Title 24 FDD Status PointsThe control shall utilize the following points to determinewhether a damper is mechanically disconnected:ECONO — Economizer Installed — Flag indicating whetheran economizer is installedRAT — Return Air TemperatureSAT — Supply Air TemperatureOA_TEMP — Outdoor Air TemperatureOCCUPIED — Currently Occupied — Flag indicating wheth-er currently in occupied modeIDF_MODE — Indoor Fan Mode — Current indoor (supply)fan mode.IDFSTATE — Indoor Fan StateFANSPEED — Commanded Fan Speed — Commanded fanspeedECONOCMD — Econo Commanded Position — Economizerposition as commanded by the ComfortLink controlECONOPOS — Econo Actual Position — Economizer posi-tion as reported by the actuatorECONCOOL — OK To Use Economizer? — Flag indicatingwhether the economizer is able to help with cooling withouttaking into account whether the supply fan is on.OKTSTMDA — OK Test Mech. D/C Act — Flag indicatingwhether the control will attempt to test for a mechanically dis-connected actuator.T24PRSAT — Title 24 Previous SAT — SAT sample taken atT24ECSMPT24ECSMP — Title 24 Econ Samp Pos — Economizer posi-tion when T24PRSAT takenT24SATCT — Title 24 SAT Check Time — Time when nextSAT sample will be taken or test for mechanically disconnect-ed actuator will be performed.ELAPSECS — Elapsed Seconds — Current ComfortLink con-trol elapsed secondsLow Suction Pressure and HighDischarge Pressure.General cooling mode problem. See Cooling Service Analysis (Table 16).Both RLV and CLV valves closed. See RLV and CLV Valve Operation, above.RDV Valve Cycling On/Off. Hot Gas Reheat mode low suctionpressure limit.Normal Operation During Mixed Circuit Subcooling and HotGas Reheat Modes at Lower Outdoor Temperatures.Circuit B Will Not Operate With CircuitA Off.Normal operation. Motormaster outdoorfan control requires operation of circuit A.NoneTable 17 — Humidi-MiZer Service Analysis (cont)PROBLEM CAUSE REMEDYLEGENDCLV — Cooling Liquid ValveCRC — Cooling/Reheat ControlRDV — Reheat Discharge ValveRH — Relative HumidityRLV — Reheat Liquid Valve