Symptom | Reason | Solution |
|---|---|---|
The Economizer Controller/ Mechanical Cooling is not operating | No input power | Use a multi-meter to check if there is 24 Vac +/- 25% (18 Vac - 30 Vac) at the POWER terminals. If there is no voltage or if the voltage is significantly low, check the transformer output voltage at the RTU. If 24 volts is not present at the transformer secondary side, check the primary line voltage to the transformer. If the line voltage is not present at the transformer primary side, check the primary power to the RTU, fuses, circuit breaker, and so on. |
Brownout | If voltage is below 17 Volts, the Economizer Controller may be in Brownout Protection mode. This mode disables all of the relay outputs. When the power is 19 Vac or higher, the Economizer Controller and RTU operate normally. | |
Y1/Y2 signal is missing from the thermostat | Mechanical Cooling doesn’t run until there is cooling demand (Y1/Y2 Active). Check the wiring from Y1I and Y2I terminals to the commercial thermostat. 24V should be present between Y1I /Y2I andY1O/Y2O respectively. | |
24 Vac~ and 24 Vac ┴ are incorrectly wired | 24 Vac power supply has polarity when all devices are powered by the same 24 Vac transformer; reversing polarity may cause a short circuit that can damage the system. Follow the transformer polarity mark, check the wring of 24V~ (or G or 24V+) and ensure that they are tied to the same polar of 24 Vac power supply; while checking the wiring of ┴ (or G0 or 24V- or COM) and ensure that they are all tied to another polar of 24 Vac power supply. | |
Free Cooling LED is solid RED | Sensor, damper or the whole working system may not work properly | Check sensor, damper or the whole working system following the detailed alarm information. |
Free Cooling LED is blinking RED | Not economizing when it should | Check the whole Economizer working system such as sensor, damper and thermostat. |
Sensor LED is solid RED | MAT/LAT sensor error | Check the MA sensor, it must be either a Type II NTC 10K or 0-10Vdc sensor. |
Outside Air (OA)/Return Air (RA) sensor error | Check the wiring and signal of OA sensor. If in Differential (DIFF) mode, check the RA sensor too. The following sensor signals are valid:
| |
Air temperature failure/fault | Check the air temperature sensor signal. The valid signal must be Type II NTC 10K or 0-10Vdc. | |
Sensor LED is blinking RED | Excess outdoor air | Check the whole Economizer working system such as sensor, damper and thermostat. |
Sensor LED is yellow | Humidity sensor error | Check humidity sensor connection, sensor signal (under range or over range) and sensor signal type. |
Sensor LED is OFF | CO2 sensor error | Check CO2 sensor connection, sensor signal (under range or over range) and sensor signal type. |
DAC LED is blinking RED | Damper slippage | Check if the damper works properly. |
DAC LED is blinking RED quickly | Actuator alarm is reported | Check if actuator output has failed, or the gap between the actuator output (in percentage) and feedback (in percentage) is bigger than the actuator tolerance setpoint (3ACT TOLR). |
DAC LED is OFF | Terminal ACT-FB is configured but no available feedback signal | Check if the feedback signal is under range or over range; check if ACT-FB is faulty or not. |
The controller has no alarm, but the Free Cooling LED never turns on even though the OA seems to be suitable for Free Cooling | Shutoff SP setting error | The shutoff temperature and/or enthalpy setpoint is incorrectly set up. Consult an HVAC professional to set up the shutoff setpoint correctly. |
OA temp is too low | The OAT is too low; therefore, there is no cooling demand. This could possibly enable anti-freeze protection. | |
OA temp is too high or too humid | In DIFF mode, even though OA temperature is lower than RA temperature, if both OA and RA temperatures exceed the high limit, Free Cooling turns off. In Differential Enthalpy control mode, even though OA enthalpy is lower than RA enthalpy, if both OA and RA enthalpy exceed the high limit, Free Cooling turns off. | |
An alarm is displayed on the LCD | Sensor, damper or the whole working system may not work properly | Check sensor, damper or the whole working system following the detailed alarm information. |
RS485 communication failure | RS485 signal or configuration error | Check wiring, configuration, Baud Rate (using mobile app) and other network communication parameters. |
Firmware update failure | Application file is damaged Operation is incorrect USB flash disk doesn’t work properly | Reload a BIN file, restart the controller, update firmware following Firmware Update or change a USB flash disk. Contact your service provider if failure still exists. |
WLAN connection failure | WLAN stick error or wrong user name and password | Plug out and plug in the WLAN stick, enter a correct user name and password, restart the controller or change a WLAN stick. If the WLAN stick is POL903.00/100, the default user name and password are Siemens-WiFi-Stick and SIBPAdmin. See document CC1N7219en for more details. |