I just got a Chronotherm III to replace my old Honeywell dial therm.
When I installed it I get the -AC message. Witch in using the groups I
found out means no Ac power. What is wierd is when I turn off auto
and switch to the fan, it comes on.
Any Ideals, Any would help
You replaced a T87F that did not have a common lead. Ten to one, the wire
that is missing, or isnt hooked up at the thermostat, or the unit since it
wasnt needed, was the C line.
You still have power to the stat, the stat just has no way to know it.
The reason your fan comes on, is that like your old stat, the auto-on switch
is nothing but that...a switch. You are completing the circuit to the fan
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