This has been asked before but there wasn't any solution. To top it off, I'm new and I can't ask the OP if he solved his problem. I may have to call him tonight. He's in the next town over. But let's see if anyone knows what the problem is.
Talking Thermostat VT1001 out of the blue starts saying "two sixty four". We had the fan circulating for a few days and all was well. Then the "two sixty four" started. So I shut the fan off. It's still doing it with the fan off.
Really unnerving when you're the only one in the house. Help!