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18-24 gauge thermostat wire
• Ensure power at the HVAC equipment is off.
• Loosen screw terminals, insert stripped wire and
• Push the excess wire back into the opening and plug
the wall opening to prevent drafts.
C – Common (optional when powered by batteries)
B – Reversing valve
O – Reversing valve
Y – 1st stage cooling / compressor
Y2 – 2nd stage cooling / compressor
G – Fan
RC – 24VAC supply cooling
R – 24VAC supply heating
W2 – 2nd stage heat / auxiliary
W – 1st stage heat / auxiliary
L – System fault indicator (optional) (heat pump only)
S1 & S2 – outdoor temperature sensor (optional)
T1 & T2 – remote temperature sensor (optional)
O and B terminals are both de-energized when system mode is
OFF or in AUTO when the heating and cooling equipment is idle.
Jumper between RC & R is used in single transformer systems
(see wiring diagrams).
SINGLE TRANSFORMER (USE JUMPER WIRE) TWO TRANSFORMERS (REMOVE JUMPER WIRE)
61000729A 8600 Tstat Install.indd 4 10/8/10 10:32:35 AM