| Description | Cause |
|---|---|
| Circuit 1 locked out due to safety chain | One of the safety chain switches opens three times. |
| Circuit 2 locked out due to safety chain | |
| Circuit 1 locked out due to low pressure | Low pressure switch trips three times in 120 minutes. |
| Circuit 2 locked out due to low pressure | |
| C1A locked out due to high pressure | HP switch trips three times in 120 minutes. |
| C1B locked out due to high pressure | |
| C1C locked out due to high pressure | |
| C2A locked out due to high pressure | |
| C2B locked out due to high pressure | |
| C2C locked out due to high pressure | |
| C1A locked out due to low pressure | |
| C1B locked out due to low pressure | |
| C1C locked out due to low pressure | |
| C2A locked out due to low pressure | |
| C2B locked out due to low pressure | |
| C2C locked out due to low pressure | |
| Unit shutdown due to smoke | A device in the shut down circuit opens. |
| Exhaust or return fan VFD failure | Abnormal condition exists on the exhaust/ return fan VFD. |
| Supply fan VFD 1 failure | Abnormal condition exists on the supply fan 1 VFD. |
| Supply fan VFD 2 failure | Abnormal condition exists on the supply fan 2 VFD. |
| No heat/cool due to unreliable space temperature | There is no reliable space temperature reference. |
| Option communication failure | Loss of communication to options board. Check SA bus wiring and connections. |
| Building system interface board communication failure | Loss of communication to building system interface board. Check SA bus wiring and connections. |
| Condenser 1 communication failure | Loss of communication to refrigeration 1 board. Check SA bus wiring and connections. |
| Condenser 2 communication failure | Loss of communication to refrigeration 2 board. Check SA bus wiring and connections. |
| Outputs disabled due to low input voltage | Loss of 24 VAC power to 24 VAC OUTPUT terminal. |
| Outputs limited due to brownout input voltage | Low voltage on 24 VAC OUTPUT terminal. |
| Cooling locked out - condensate overflow | Check condensate drain for clogs. |
| Unit locked out due to high duct static pressure | Duct static pressure (DSP) exceeds setpoint. |
| Unit locked out - airflow proof failure | APS does not close when expected on fan start-up. |
| C1A locked out - exceeded operating envelope limits | Variable speed drive compressor envelope control: This output shows lockout when three variable speed drive compressor operating envelope shutdown events occur within two hours of compressor runtime. |
| C1A locked out due to oil switch | C1A oil switch open. Check crankcase oil level. |
| Furnace module 1 lockout | Heating section 1 shutdown due to ignition control module. Check module for fault enumerator. |
| Furnace module 2 lockout | Heating section 2 shutdown due to ignition control module. Check module for fault enumerator. |
| Furnace module 3 lockout | Heating section 3 shutdown due to ignition control module. Check module for fault enumerator. |
| Description | Cause |
|---|---|
| Unit shutdown airflow validation fail | Heating and cooling shutdown, blower operation is not proven. Check APS, DSP. |
| Circuit 1 shutdown due to low pressure | Low airflow, dirty filters, ice on coil, low charge. |
| Circuit 2 shutdown due to low pressure | |
| C1A shutdown due to high pressure | Dirty condenser coils, condenser fan failure, over charge. |
| C1B shutdown due to high pressure | |
| C1C shutdown due to high pressure | |
| C2A shutdown due to high pressure | |
| C2B shutdown due to high pressure | |
| C2C shutdown due to high pressure | |
| C1A shutdown due to low pressure | Low airflow, dirty filters, ice on coil, low charge. |
| C1B shutdown due to low pressure | |
| C1C shutdown due to low pressure | |
| C2A shutdown due to low pressure | |
| C2B shutdown due to low pressure | |
| C2C shutdown due to low pressure | |
| HGRH locked out - valve stuck open | Hot gas is flowing to reheat coil when no flow is expected. |
| HGRH locked out - valve stuck closed | Hot gas is not flowing to reheat coil when flow is expected. |
| Main controller calibration error | Cycle power to the unit. If error returns, contact technical support. |
| Option controller calibration error | |
| Condenser 1 controller calibration error | |
| Condenser 2 controller calibration error | |
| Building system interface board controller calibration error | |
| DAT sensor failure | Sensor input out of expected range. Open or shorted circuit. |
| OAT sensor failure | |
| RAT sensor failure | |
| Building pressure sensor failure | |
| Return fan pressure sensor failure | |
| Evaporator coil temperature 1 sensor failure | |
| C1A shutdown - exceeded operating envelope limits | Variable speed drive compressor envelope control: This output shows disabled when a shutdown occurred due to the variable speed drive compressor exceeding its operating envelope limits. The compressor must remain off for 10 minutes. |
| Description | Cause |
|---|---|
| Circuit 1 shutdown due to safety chain | One of the safety chain switches in circuit 1 opens. |
| Circuit 2 shutdown due to safety chain | One of the safety chain switches in circuit 2 opens. |
| MAT sensor failure | Sensor input out of expected range. Open or shorted circuit. |
| Outside air humidity sensor failure | |
| Pre-filter pressure sensor failure | |
| Final filter pressure sensor failure | |
| Return air humidity sensor failure | |
| Heat entering temperature sensor failure | |
| Outside airflow sensor failure | |
| Discharge air pressure sensor failure | |
| Return air pressure sensor failure | |
| Sensor calibration fault | Sensor or sensors fails calibration test. Cycle power to unit. If error returns, contact technical support. |
| C1 liquid pressure sensor failure | Sensor input out of expected range. Open or shorted circuit. |
| C2 liquid pressure sensor failure | |
| C1 liquid temperature sensor failure | |
| C2 liquid temperature sensor failure | |
| C1 suction pressure sensor failure | |
| C2 suction pressure sensor failure | |
| C1 suction temperature sensor failure | |
| C2 suction temperature sensor failure | |
| Zone air humidity sensor failure | |
| ZT sensor failure | |
| OAQ sensor failure | |
| Return air quality sensor failure | |
| Discharge air humidity sensor failure | |
| Exhaust heat recovery temp sensor fail | |
| Slab humidity sensor failure | |
| Slab temperature sensor failure | |
| DAT cannot reach cooling setpoint | Expected discharge air temperature does not occur due to high evaporator air temperature. |
| DAT cannot reach heating setpoint | Expected discharge air temperature does not occur due to low evaporator air temperature. |
| Unit continuous runtime exceeds limit | The AHU_AIRFDD_RunContinuous module is designed to alarm if the unit runs continuously beyond a defined time limit. The default is 23 hours. This means that the unit does not turn off by a time schedule. If the unit is designed to run continuously (such as a hospital), then adjust the alarm_delay to 0 in order to suppress the alarm. |
| Trim and respond not changing setpoint | The AHU_AIRFDD_SPNotChanging module is designed to set an alarm if the setpoint input does not change in value during the alarm_delay interval. This is primarily used to make sure that the trim and respond setpoint adjust features are working properly. These features are usually in the supervisory controller. |
| Idle time while occupied exceeds limit | The AHU_AIRFDD_UnitDownInOcc module is designed to set an alarm if the unit is shut down for a certain time period during the occ mode. |
| Economizer not economizing when it should | Economizer damper does not open as commanded. Damper is stuck closed. |
| Economizer economizing when it should not | Economizer damper does not close as commanded. Damper is stuck open. |
| Economizer damper not modulating | Economizer damper does not respond to a change in the percent open or close command. |
| Excess outdoor air | Too much outside air introduced into the unit. Outside air damper failure. |
| Space temperature cooling alarm | Space temperature not at expected temperature within time period. |
| Space temperature heating alarm | |
| Airflow detected without supply fan | Airflow indicates when blower expected to be off. Check APS and/or Duct Static Pressure. |
| Unit has received a purge request | Unit in a purge mode by a contact closure. |
| UV light needs service | UV light module triggers this alarm. |
| Low OAT cooling cutout | OAT is below the cooling lockout setpoint. |
| Heating locked out due to OAT | OAT is above the heating lockout setpoint. |
| Hot water freezestat open to prevent coil freeze | Air temperature at hot water heating coil is below setpoint. |