Hi,
I installed this t-stat in February 2005 and it worked fine through the heating system with my carrier heat pump. The heat pump says it was manufactured in 9/86... So it was the original one put into the home. I tried to get A/C this weekend and no luck. I went to the Honeywell website for troubleshooting and they suggested that I take out the wire going to the "C" (which for my wiring is the blue wire). I did that and it still is only providing fan circulation. Any suggestions would be greatly appreciated.
Thanks!