Key Takeaways
What is the difference between Y1 and Y2?
In standard systems, Y/Y1 controls the first stage of cooling, and Y2 controls the second stage.
Can I use Y2 instead of Y1?
Y, Y1, Y2: Whenever your thermostat calls for cooling, the Y wire is used to send a signal to your HVAC system telling it to fire up the air conditioner. Y1 and Y2 wires might be used instead if you have a two-stage system (i.e. a high level for extremely hot or cold days, and a low level for mild days).
What is Y1 on a thermostat?
In most systems, the Y or Y1 wire controls your cooling system. If you have a heat pump, your Y or Y1 wire controls your compressor. Your compressor is responsible for heating and cooling your home. The G or G1 wire controls your fan.
What is the Y2 terminal on a thermostat?
Y2 – This is the thermostat terminal for cooling second stage if your system is so equipped. Many systems only have a single compressor but if you have two compressors which should only operate off of one thermostat then you need the Y2 thermostat terminal for second stage cooling.