6
Replace the old labels with the enclosed new labels:
Replacing Wiring Labels
Old New Type
F, G G Fan control relay
O O Cool active reversing valve
B B Heat active reversing valve
Y, Y6 Y Cooling control
H, W, 4 W
Heating control
C Transformer, common side
M, 4, RH, RS, R R Transformer, hot side
C Y or C
If the C terminal is the cooling control, connect to Y terminal; if
it is the common side of the transformer, connect to C terminal