If your TEC, which is located on the door of the enclosure, is always “ON” the most likely causes are one of the following:

1. The digital output that controls the TEC is not set to automatic.  In order to verify the setting of the digital output, perform the following:

1.    Navigate in DCTools or on the Controller interface to Digital Outputs.

2.    Scroll down to "TE On".

a.      If the state is Active, check to see if control state is automatic or manual.

i.      If it is manual, change the control state to automatic. The TEC should shut off.
ii.     If it is automatic, the TEC is trying to cool down the enclosure. Check the status of the alarms, and make sure a high temperature alarm           is not activated.
iii.    If the state is inactive, and the TEC is still on, the most likely cause is a bad relay. 

2. The relay that controls the TEC is stuck closed.  If the relay is stuck in the closed position, the TEC will remain “ON” and the relay needs to be replaced.  To test if a relay is working correctly after replacement, go into DCTools or the Controller interface after installation of a new relay, and test if you can manually control the relay and TEC, in the same menu as step 1.