Let’s start with the alert or code that begins with the letter T. Usually, this is not a full shut down alert code. In this mode the circuit with the problem code will not run and the secondary circuit takes the lead and attempts to condition the space. So, if you were to check alarm history you would see alerts starting with a T for a specific circuit depending on how many are available to the unit. 

Now let’s go over when the Comfort Link controller has an alarm light indicated on the unit. It is in an alarm state and will not run without technician intervention. The controller has to be reset and the responsibility falls on the technician to troubleshoot the issue.

Where do alerts or alarms start? In the manual it states they start as pre-alerts. This is defined below :

• P — Pre-Alert: Part of the unit is temporarily down. The alarm is not broadcast on the CCN network. The alarm relay is not energized. After an allowable number of retries, if the function does not recover, the pre-alert will be upgraded to an alert or an alarm

For both alerts and alarms they start out as pre-alerts. They get upgraded after a certain amount of startup has been tried. These usually follow a three-strike system or something similar. On the third start if the issue persists it will either go into alert or alarm depending on what it is.

Depending on what code the unit is indicating it can lead you in the right direction. Confirm the controls manual when you can to ensure that the right error code is being defined. Not all Comfort Link manuals are the same nor alarm and alert codes are the same. Each unit differs.