6
If your LCD is blank, or displaying LO BAT, the batteries are not installed or need to be changed. We
suggest you change the batteries at least once a year, or whenever the LO BAT warning displays.
Note: After installing new batteries, you have to reset the room temperature setting and the
differential setting.
Step 1: Move the Cool/Off/Heat switch into the Off position.
Step 2: Move the Fan Auto/On switch into the Auto position.
Step 3: Remove the cover, and install the two “AA” alkaline batteries into the battery compartment.
Proper battery installation is important! Make sure the positive ends of the batteries match the
positive terminals in the battery compartment.
If the display is on, the batteries are installed properly.
Installing and Changing Batteries (SC2000 only)
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