Model and S/N's help greatly. Way too many versions out there to answer the question. With that said, I was able to find some info on that series controller. Could be a loose or broken wire. Sounds like a call back to me. Should be a simple fix.

https://www.star-supply.com/content/Trane%20Alert%20Codes.pdf

 

Thanks very much eggs, that’s a huge relief, I’ll see if they can get back out to look at it.

 

Hi eggs, so I did get the original tech out to look at it today. The fault is with a communicating sensor (AZONE940) in the attic zone which is no longer communicating with the unit. The main thermostat is an American Standard AZONE 950. However he tells me couldn't tell whether it's a wiring problem or a problem with the sensor, says he can't test the wire because he doesn't know where the ends are. A bit of an impasse. He puzzled around for a few hours and then came back with the suggestion that the control board needs to be replaced because it's making clicking sounds, and that's causing the communication problem. He wants to order a new one and replace it. Does that sound plausible? Is it worth it to get an authorized Trane dealer to look at it?

 

We call that a parts changer - keep changing parts until it works again. Although I am authorized to warranty and repair Trane, I am not familiar with that system. If it were a Tracer/Tracker - I could help, but impossible to know all the different types of systems out there - guessing over 100,000 different types and styles of controllers in use today. If you have a contractor that deals specifically with that controller, that would be best. Either way, it really should not be that hard to find the start and end of that cable. Do not change out a board until you know exactly the issue.

 

Exactly what I was afraid of. I'm going to get the original installer out to come look at it today. I also have a third opinion lined up, a Trane/American Standard certified company. Fingers crossed they can figure it out. Thanks again friend.