Look at the thermostat wiring photo you took. The following are wiring diagrams for common
systems, please confirm you have a C connected to your old thermostat.
Terminal
RC
RH
C
G
Y
Y2
W/E
O/B/W2
Conventional System
Power for cooling, 24V
Power for heating, 24V
Common wire, 24V
Fan
Power for cooling, 24V
Power for heating, 24V
Common wire, 24V
Fan
1st Stage Cool
2nd Stage Cool
1st Stage Heat
2nd Stage Heat
1st outdoor Stage Heat
2nd outdoor Stage Heat
1st Stage Auxiliary/Emergency Heat
Changeover (reversing valve)
connection for heat pump
Heat Pump System
10