Carrier 48HG014 Controls Operation And Troubleshooting

Contents

Carrier 48HG014 Controls Operation And Troubleshooting Manual pdf 32 page image

32Alarms and Alerts — Alarms and alerts are warnings ofabnormal or fault conditions, and may cause either one circuitor the entire unit to shut down. They are assigned codenumbers and descriptions as described below. The descriptionfor an alarm can be viewed from the Scrolling Marquee displayby pressing and keys simultaneouslywhile displaying the alarm code number. Be sure to expand thedescription for each alert and alarm, because in some cases,there are different possible descriptions for each number.Table 27 contains a detailed description of each alarm and alertcode error and possible cause. Possible actions taken by theelectronic controls are:• nothing• adding a “strike” to the strike counter for a particularcircuit• shutting down a circuit• shutting down the unit.When a “strike” is added, the circuit is shut down for15 minutes. After 3 strikes, the circuit will be permanently shutdown until the alarms are reset via the Scrolling Marqueedisplay. More information concerning alarm handling can befound in Alarm Handling on page 31.DIAGNOSTIC ALARM CODES AND POSSIBLECAUSESAlert Codes 51, 55 and 59 (Compressor Safety) — Alertcodes 51, 55, and 59 are for compressors A1, B1, and C1, re-spectively. These alerts occur when the Current Sensor (CS)does not detect compressor current during compressor opera-tion. When this occurs, the control turns off the compressor andlogs a strike for the respective circuit. These alerts resetautomatically.The possible causes are:1. High-pressure switch (HPS) open. The HPS-pressureswitch is wired in series with compressor relays on theMBB. If the high-pressure switch opens during compres-sor operation, the compressor stops, and the CS no longerdetects current, causing the control to activate this alert.2. Compressor internal protection is open.3. Wiring error. A wiring error might not allow the compres-sor to start.To check out alerts 51, 55 and 59:1. Turn on the compressor in question using Service Testmode. If the compressor does not start, then most likelythe problem is one of the following: HPS open, open in-ternal protection, incorrect safety wiring, or incorrectcompressor wiring.2. If the compressor starts, verify that the indoor and out-door fans are operating properly.3. If the CS is always detecting current, then verify that thecompressor is on. If the compressor is on, check the con-tactor and the relay on the MBB. If the compressor is offand there is no current, verify CS wiring and replace ifnecessary.4. Return to Normal mode and observe compressor opera-tion to verify that compressor current sensor is workingand condenser fans are energized after compressor starts.Alert Codes 51, 55 and 59 (Current Detected After Turnoff)— Alert codes 51, 55, and 59 are for compressors A1, B1, andC1, respectively. These alerts occur when the Current Sensor(CS) detects current when the compressor should be off. Whenthis occurs, the control turns off the compressor and logs astrike for the respective circuit. Use the Scrolling Marquee toreset the alert.The possible causes are1. Welded contactor.2. Frozen compressor relay on MBB.To check out alerts 51, 55 and 59:1. Place the unit in Service Test Mode. All compressorsshould be Off.2. Verify that there is not 24V at the contactor coil. If there is24V at the contactor, check relay on MBB and wiring.3. Check for welded contactor.4. Verify CS wiring.5. Return to Normal mode and observe compressor opera-tion to verify that compressor current sensor is workingand condenser fans are energized after compressor starts.Alert Codes 64, 65 and 80 (Condensing Temp. Failure) —Alert codes 64, 65, and 80 are for circuits A, B and C, respec-tively. These alerts occur when the temperature is outside therange –40 to 240 F (–40 to 116 C). When this occurs, thecontrol uses the outdoor temperature to control the outdoorfans. If the outdoor temperature is greater than 40 F, the circuitwill run at Fan Level 2. If the outdoor temperature is less than35 F, the circuits will run at Fan Level 1. If the outdoor-air sen-sor is also bad, the circuit will be locked out, otherwise thisalert resets automatically.The cause of the alert is usually a faulty thermistor, ashorted or open thermistor caused by a wiring error, or a looseconnection.Alert Code 73 (Outside Air Temp. Failure) — This alert occurswhen the temperature is outside the range –40 to 240 F (–40 to116 C). This alert resets automatically. The cause of the alert isusually a faulty thermistor, a shorted or open thermistor causedby a wiring error, or a loose connection.Alert Code 74 (Space Temp. Failure) — This alert occurswhen the temperature is outside the range –40 to 240 F (–40 to116 C). This alert will only occur if the unit is in Space SensorMode. The unit will shut down if this alert occurs while inSpace Sensor mode. This alert resets automatically. The causeof the alert is usually a faulty thermistor in the T55, T56, orT58 device, a shorted or open thermistor caused by a wiring er-ror, or a loose connection.Alert Code 75 (Supply Air Temp. Failure) — This alert occurswhen the temperature is outside the range –40 to 240 F (–40 to116 C). This alert resets automatically. The cause of the alert isusually a faulty thermistor, a shorted or open thermistor causedby a wiring error, or a loose connection.Alert Code 80 (Condensing Temp. Failure) — See Alert 64.Alert Codes 92, 93, 101 (Suction Pres. Trans. Failure) — Alertcodes 92, 93, and 101 are for circuits A, B and C, respectively.These alerts occur when the pressure is outside the range 0.5 to134.5 psig. A circuit cannot run when this alert is active. Usethe Scrolling Marquee to reset the alarm. The cause of the alertis usually a faulty transducer, faulty 5-V power supply, or aloose connection.Alert Codes 102, 103, 104 (Current Sensor Failure) — Alertcodes 102, 103, and 104 are for compressors A1, B1, and C1,respectively. These alerts occur when the output of the currentsensor (CS) is a constant high value. These alerts reset auto-matically. The cause of the alert is a wiring error or a loose con-nection. If the problem cannot be resolved and the CS boardmust be replaced, the CS board can be temporarily disabledwhile securing a replaced board. A CS board is disabled by set-ting the corresponding configuration to DISABLE (CS.A1,CS.B1 or CS.C1).ESCAPE ENTER202→→