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Wiring compatibility

CFresno
Community Member

Hi

I connected my thermostat and the furnace works but makes a strange noise, I reinstalled the old thermostat and everything works fine.
These are my cables:

Y, G, W, RC/O (jumper with RH/B)

Thanks!

 

3 REPLIES 3

zoeuvre
Community Specialist
Community Specialist

Hi CFresno, 

 

Yikes! If you've experienced strange noises from your furnace after connecting your Nest Thermostat, it's possible that there may be an issue with the wiring or configuration. Could you send us the wiring photo of your previous thermostat so I can take a closer look? Also, try these:

 

  1. Double-check the wiring connections at both the furnace and the Nest Thermostat. Ensure that each wire is securely connected to the corresponding terminal and that there are no loose or frayed wires. Make sure that the wires are properly stripped and inserted into the terminal blocks.
  2. It's possible that the wiring configuration needs adjustment. In your case, you mentioned a jumper between RC and RH/B terminals. This setup suggests that you have a combined heating and cooling system. However, it's important to ensure that the wiring matches the specific requirements of your furnace and the Nest thermostat. Consider consulting the Nest Thermostat's installation guide or contacting Nest support for assistance in properly configuring the wiring for your system.
  3. Try power cycling your furnace and Nest Thermostat. Turn off the power to your furnace by switching it off at the circuit breaker or disconnecting the power source. Then, turn off the Nest Thermostat by going to the settings menu and selecting "Turn System Off." After a few minutes, restore power to the furnace and turn the Nest Thermostat back on. This can help reset the system and resolve any temporary issues.

 

Remember to prioritize safety when working with your furnace or electrical systems. If you're uncomfortable or unsure about any steps, it's best to consult a professional to avoid any risks or further issues.

 

Let us know how that works.

 

Best,

Zoe

CFresno
Community Member

Hi, Thanks for your answer.

I can't load pictures.

https://x.com/cfresnoossa/status/1745873602388369814?s=20

I put the picture in my X (Twitter) account.

Thanks

zoeuvre
Community Specialist
Community Specialist

Hi there, 

 

Thanks for getting back to us, and I'm sorry for the late response. When your HVAC system makes strange noises such as chattering, stuttering, clicking, or thumping, this means that a C wire is required. In cases like these, the best solution is for you to contact a Nest Pro. The Nest Pro can diagnose and help fix any problems with your system and thermostat installation. If needed, they can also wire an additional C wire or connect the power connector accessory to the Nest Thermostat.

 

Let us know if that helps.

 

Regards,

Zoe