I wasn't very specific, ... It's a Trane XE90, three years old, seems to be
working fine (right now), and the red light blinks 2 times per second. -B

"B" wrote in message
...
In my attic there's a Trane central heat/AC unit. There's a round "window"
the size of a quarter, and peering into that window I see a blinking red
light. Whats up with that?
-B