HVAC Thermostat Not Working After Trying to Replace

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HVAC Thermostat Not Working After Trying to Replace

Today I tried to replace my existing thermostat with a Nest Learning Thermostat.

My old thermostat is a Bryant thermostat and Bryant HVAC unit.

The thermostat has Y G C W and Rh with a jumper to Rc.

Connected the Nest as suggested and got this error message.

Google tech support wasn't able to help and now after trying to reconnect my old thermostat to have AC running, that won't work now either.

The thermostat won't turn on at all (without batteries) but it turns on with batteries but won't turn on the compressor.

Any suggestions? I have two units (upstairs and downstairs) - it is the downstairs unit that is affected.

We have a crawl space and I can't tell anything obviously wrong (like drain pan etc).

Question from user me4help at hvacadvice at reddit.

Answer:

It sounds like you're experiencing some technical issues with the installation of your Nest Learning Thermostat and the functionality of your HVAC system. Here are a few troubleshooting steps you can take to try to resolve the issues:

1. Check Wiring Connections: Double-check the wiring connections on both the Nest thermostat and the HVAC unit. Make sure that each wire is properly connected to the corresponding terminal on both ends. Ensure that there are no loose connections or exposed wires.

   
   

2. Check Compatibility: While Nest thermostats are compatible with many HVAC systems, there can be exceptions. Verify that your Bryant HVAC system is compatible with the Nest Learning Thermostat. You can refer to the Nest website or consult the Nest compatibility guide to confirm compatibility.

   
   

3. Check Fuse and Circuit Breaker: If the old thermostat is not working with the HVAC system after attempting to reconnect it, there might be an issue with the power supply. Check the fuse and circuit breaker associated with your HVAC system to make sure they haven't tripped.

   
   

4. Check Battery Contacts: Since you mentioned that the old thermostat is turning on with batteries but won't control the compressor, it's possible that the battery contacts are not making proper contact. Make sure the battery contacts are clean and secure.

   
   

5. Check Compatibility with Dual Systems: If you have two HVAC units for upstairs and downstairs, ensure that the Nest thermostat is compatible with dual-zone systems. Some thermostats require additional wiring or configurations for multi-zone systems.

   
   

6. Nest Wiring Configuration: Verify that you have configured the Nest thermostat correctly based on your HVAC system's wiring. The Nest app or manual should provide guidance on how to set up the thermostat for your specific wiring configuration.

   
   

7. Consult HVAC Professional: If you've tried these troubleshooting steps and are still experiencing issues, it might be a good idea to consult a professional HVAC technician. They can diagnose the issue more accurately and help you resolve any compatibility or wiring problems.

   
   

8. Factory Reset Nest Thermostat: If you want to return to the original configuration, you can perform a factory reset on the Nest thermostat. Refer to the Nest's official documentation on how to perform a reset.

   
   

Remember that working with HVAC systems involves electrical components, and if you're not comfortable or experienced with these systems, it's best to seek professional help to prevent any further complications or safety hazards.

Answer from user Downtown-Fix6177 at hvacadvice at reddit.