Wiring for 2-stage thermostat and 2-stage furnace with single stage cooling
Ok so I figured it out. I probed the pins on the back of the thermostat to see which pins were being energized when it was calling for cooling. Turns out it energizes Y1, not Y2. Makes sense since it does support 2 stages for both heating and cooling. So I have my &quot;cooling&quot; wire at the Y1 terminal at the thermostat and Y/Y2 at the furnace. This wiring allows the cooling to work at the required high flow. Works as expected now. Final revised wiring diagram below.