48/50PD
only the outdoor temperature to control the outdoor fans. If both the SCT and OAT fail, then circuit shutdown alarm will occur also. 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 T066 - Circuit A Saturated Suction Temperature Thermistor Failure
This alert occurs when the unit’s suction transducers are turned off internally. Cooling will not operate. This is usually due to a network force on a non exposed CCN point. Reload factory defaults or reinstall software on the MBB. Consult the network manager if alert continues.
Alert Code T073 - Outdoor Air Temperature Thermistor Failure
This alert occurs when the temperature is outside the range
Alert Code T074 - Space Temperature Thermistor Failure
This alert occurs when the temperature is outside the range
Alert Code T075 - Supply Air Temperature Thermistor Failure
This alert occurs when the temperature is outside the range
Alert Code T076 - Return Air Thermistor Failure
This alert occurs when the temperature is outside the range
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.
IMPORTANT: An ECB must be installed to use the space relative humidity sensor.
Alert Code T092 - Circuit A Suction Pressure Transducer Failure
This alert occurs 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
Alert Code T102 - Compressor A1 Current Sensor Failure
This Alert indicates that Current Sensing A1 (CS.A1) has been enabled. The unit does not support the use of a current sensor at
this time. Change the CS.A1 to disable and this alert will clear and not return.
(Configuration→COOL→CS.A1)
Alert Code T110 - Circuit A Loss of Charge
This alert has “Service Test” text that will be displayed if the alert occurred during service test. This alert occurs when the compressor is OFF and the suction pressure is less than 5 psig and OAT is greater than
Alert Code T126 - Circuit A High Discharge Pressure
This alert has “Service Test” text that will be displayed if the alert occurred during service test. This alert occurs when alert T051 is active while the appropriate condensing temperature is greater than 150_F. This alert 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
Alert Code T133 - Circuit A Low Refrigerant Pressure
This alert has “Service Test” text that will be displayed if the alert occurred during service test. This alert occurs 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
Alert Code T143 - Circuit A Failure to Pressurize
This alert has “Service Test” text that will be displayed if the alert occurred during service test. This alert occurs when the compressor turns on and the difference between suction and discharge pressure is less then the Ckt A Minimum Pressure (Configuration→COOL→SST→PSI.D). The pressure difference must be greater then PSI.D (default is 20 psi) after 60 seconds and stay above it while running the compressor. This alert causes 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.
Alert Code T153 - Real Time Clock Hardware Failure
This alert occurs when the RTC clock chip on the MBB is not responding. Time and date functions will not operate, such as local occupancy schedules. The unit will default to 24/7 unoccupied mode. Recovery is automatic but MBB board replacement may be necessary. Cycling power to the control and reconfiguring the time and date should be tried before board replacement.
Alarm Code A154 - Serial EEPROM Hardware Failure
The unit will completely shut down. The serial EEPROM chip on the MBB, which stores the unit’s configuration, is not responding.
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