Is there any trick to replacing a defunct thermostat? The clock on my old Honeywell Chromotherm has stopped functioning and the mechanism may be obsolete. If I need to replace the whole unit, is it necessary to cut off the electricity leading to the thermostat?
Thanks much.

Warren Cassell

Turn off power to the inside unit.

Mark down each color of wire and where the wire landed on the old thermostat W,R,Y,G,etc.

Buy new thermostat and follow the directions EXACTLY.

You should be OK.

NOTE do not forget to identify/mark/write down/ where the old wires were on the old thermostat.

You would not believe that most people do not follow the directions and do not identify the wires before removal.