3rd gen learning wiring for 2 stage heat and 2 stage cool

[Please384234568]

Please help! I got my thermostat in October and wired it perfectly for 2 stage heating. Now the outside temps suddenly jumped overnight, so I switched to cool, and the stage 2 cooling will not stay on. It kicks on for a second and then kicks off.

I seem to remember reading that a wire needs to be switched when the seasons change from heat to cool, but I can't remember what that wire is.

Please help! My house will not cool down right now!

I can't figure out how to post a picture from my phone, but I have wires in:

Y1 Y2 G Rc W1 W2 Aux

2 stage heat worked perfectly all winter.

[Ivan_R]

Hi Please384234568,

Thanks for posting! There shouldn't be a wire you need to physically swap between heating and cooling seasons with a Nest thermostat. Two potential causes could be at play here:
 

Wiring Misconfiguration: Double-check your Nest wiring, especially the Y wires. Here's what to look for:
 

• Ensure both Y1 and Y2 wires are securely connected to their respective terminals on the Nest and your HVAC system's control board. Loose connections can cause erratic behavior.
   
• Verify the Y2 wire is correctly configured in the Nest settings. Nest thermostats typically use the Y2 terminal for second-stage cooling. You can check this by going to Settings > Equipment > HVAC and ensuring Y2 for Stage 2 Cooling is selected.
   

System Issues: There's a possibility the issue lies with your HVAC system itself. Here's what to try:
 

• Power Cycle: Turn off the power to your HVAC system at the breaker box for 30 seconds, then turn it back on. This can sometimes reset minor glitches.
   
• Air Filter Check: A clogged air filter can restrict airflow and lead to the system shutting off prematurely. Check and replace your air filter if needed.

You can also try additional troubleshooting steps by referring to this help article: Troubleshoot strange heating or cooling behavior.

Let me know hot it goes!

Regards,

Ivan