Carrier 48/50PM C16-28, 48/50PG C03-14 manual Alert Code T076 − Return Air Thermistor Failure

Alert Code T075 − Supply Air Temperature Thermistor Failure

This alert occurs when the temperature is outside the range –40_to 240_F (–40_to 116_C). Economizer cooling and adaptive compressor staging cannot occur while this alarm is active. This alert resets automatically. The cause of the alert is usually a faulty thermistor, a shorted or open thermistor caused by a wiring error, or a loose connection.

Alert Code T076 − Return Air Thermistor Failure

This alert occurs when the temperature is outside the range –40_to 240_F (–40_to 116_C). This alert will only occur if the unit is configured for a return air sensor. Economizer differential dry bulb control will not be allowed during this alert. This alert resets automatically. The cause of the alert is usually a faulty thermistor, a shorted or open thermistor caused by a wiring error, or a loose connection.

Alert Code T077 − Space Relative Humidity Sensor Failure

This alert occurs when the input is less than 3.5 mA and the sensor is configured as installed. If a humidistat is not installed, then dehumidification will not be functional. Check sensor and wiring. This alert clears automatically.

NOTE: An ECB must be installed to use the space relative humidity sensor.

Alert Code T080 − Circuit C Saturated Condensing Temp Thermistor Failure

See Alert T064

Alert Code T081 − Circuit Saturated Suction Temperature Thermistor Failure

See Alert T066

Alert Codes T092, T093, T101 – Circuit Suction Pressure Transducer Failure

Alert codes T092, T093, and T101 are for circuits A, B and C, respectively. These alerts occur when the board does not properly read the transducer voltage. A circuit cannot run when this alert is active. Use the Scrolling Marquee to reset the alarm. The cause of the alert is usually a faulty transducer, faulty 5−v power supply, or a loose connection.

Alert Codes T102, T103, and T104 − Compressor Current Sensor Failure

Alert codes T102, T103, and T104 are for compressors A1 and A2, B1 and C1, respectively. These alerts occur when the output of the current sensor (CS) is a constant high value. These alerts reset automatically. The cause of the alert is a wiring error or a loose connection. If the problem cannot be resolved and the CS board must be replaced, the CS board can be temporarily disabled while securing a replaced board. A CS board is disabled by setting the

corresponding configuration to DISABLE (Configuration→COOL→CIR.A→CS.A1, CS.B1 or CS.C1).

Alert Codes T110, T111, and T140 – Circuit Loss of Charge

Alert codes T110, T111, and T140 are for circuits A, B and C, respectively. These alerts have “Service Test” text that will be displayed if the alert occurred during service test. These alerts occur when the compressor is OFF and the suction pressure is less than 5 psig and OAT is greater than –5_F for 1 continuous minute. Use the Scrolling Marquee to reset the alert. The cause of the alert is usually low refrigerant pressure or a faulty suction pressure. These alerts only occur when the compressor is OFF because the low refrigerant pressure alarms (alerts T133, T134 and T141) handle this situation when the compressor is operating.

Alert Codes T126, T127 and T142 − Circuit High Discharge Pressure

Alert codes T126, T127, and T142 are for circuits A, B and C, respectively. These alerts have “Service Test” text that will be displayed if the alert occurred during service test. These alerts occur when alerts T051, T055, or T059 are active while the appropriate condensing temperature is greater than 150_F. These alerts reset automatically. The cause of the alert is usually an overcharged system, high outdoor ambient temperature coupled with dirty outdoor coil, plugged filter drier, or a faulty high−pressure switch. See Alerts T051, T055 and T059 for diagnostic procedure.

Alert Codes T133, T134 and T141 − Circuit Low Refrigerant Pressure

Alert codes T133, T134 and T141 are for circuits A, B and C, respectively. These alerts have “Service Test” text that will be displayed if the alert occurred during service test. These alerts occur when the compressor is operating and the evaporating temperature (converted from the suction pressure) is less than

configured low suction control levels, Configuration→COOL→SST→SST.1 (Low Suction — Level 1) or SST.2 (Low Suction — Level 2) or SST.3 (Low Suction Level 3). The circuit SST value must be less than SST.1 (for 5 minutes), SST.2 (for 4 minutes), or SST.3 (for 3 minutes when using the economizer and 1.5 minutes when not using the economizer) for the alert to occur. When the outdoor temperature is less than 40_F, the above values are reduced 1_F for every 2_F the OAT is below 40_F. An alert will also occur if the circuit SST value is less than SST.3 –5_F for 20 seconds and the outdoor temperature is above 40_F. All the above timers will reset if the suction temperature rises above SST.O for 1 minute. These alerts cause a strike for the respective circuit. If the OAT is less than 10_F, the circuit will shut down without a strike. These alerts will activate when the coil becomes frosted. However, during the 15−minute reset period, the coils will thaw and strike should clear at restart if there is nothing else wrong with the circuit. The alert resets automatically. The cause of the alert is usually low refrigerant charge, dirty filters, evaporator fan operating backwards, loose or broken belt, plugged filter drier, faulty transducer, excessively cold return air, or stuck open economizer when the ambient temperature is low.

Alert Codes T140 − Circuit C Loss of Charge

See Alert T110.

Alert Codes T141 – Circuit C Low Refrigerant Pressure

See Alert T133.

Alert Codes T142 – Circuit High Discharge Pressure

See Alert T126.

Alert Codes T143, T144 − Circuit Failure to Pressurize

Alert codes T143, T144, and T145 are for circuits A, B, and C, respectively. These alerts have “Service Test” text that will be displayed if the alert occurred during service test. These alerts occur when the compressor turns on and the suction pressure does not drop at least 10 PSIG and stay there for the first 20 seconds AND the condensing temperature does not rise at least 5_F and stay there for the first 65 seconds (both conditions have to occur). These alerts cause a strike for the respective circuit. The alert resets automatically. The cause of the alert is usually compressor wiring causing reverse rotation or a faulty compressor.

48/50PG and PM

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