Heat won’t stay on nest gen 3

[Dk1980]

Just connected 2 nest gen 3 in place of my old thermostats. 

downstairs unit went smoothly and seems fine 

upstairs however, I connected everything the same way but when I went to test the heat the system would quickly cycle btwn on and off and not stay on. 

I triple checked the wiring and connections. The air handler runs fine when I test the fan but not when I test the heat. Tried resetting the system. Nothing seemed to work. I reconnected my old thermostat and the heat runs fine. It’s a gas system

[Markjosephp]

Hello Dk1980,

Thanks for reaching out! It sounds like you've put in some effort to upgrade your thermostats to Nest Learning Thermostat, and I'm sorry to hear about the issues you're facing with the upstairs unit's heating cycle. Troubleshooting can be challenging, but let's try to figure this out together.

First, it's great that you've already triple-checked the wiring and connections. Since the air handler runs fine when you test the fan but not when testing the heat, it suggests there might be an issue with the heating system integration. To narrow down the problem:

• Do they have a C-wire connection?
• Check the configuration settings. There might be an option related to the heating cycle or a setting that needs adjustment. Ensure that the thermostat is set up correctly for your specific heating system.
• Voltage issues. Gather the power readings in the Technical Info settings.

Keep me posted.

Regards,
Mark