In all versions of the AIRSYS Lead/Lag Controller (ASLLC) software, if the sensor is disconnected, an A19 alarm will be triggered and displayed on the pLD.  In most cases, the cause for the alarm is that the sensor connector has been pulled loose from the sensor itself.  To check this, remove the plastic case off the sensor and verify that the cable is securely connected to the sensor board (see video below).  If it has come loose, re-set the connector as shown in the video and test by using the Step Test.

In rare cases in newer version of the ASLLC software (revision 13B40 and greater), an A19 alarm could indicate that the sensor has failed.  If you have verified that the connector is securely attached to the sensor and you are still receiving an A19 alarm, please contact us and we can assist in further troubleshooting.

HVAC Technical Support:

(855) 874-5380