Google Nest Error Code W5: How to Fix It

Q: What does Nest error code W5 mean?

Error code W5 means your Nest thermostat detected two transformers in your HVAC wiring. This usually happens when both Rh and Rc wires are connected or when there's an improper jumper wire, which can damage your equipment.

Q: Can I ignore the W5 error on my Nest thermostat?

No, you should not ignore error W5. Having two transformers connected can cause electrical conflicts and potentially damage your HVAC system or thermostat. Fix this error promptly to prevent equipment damage.

Q: Which red wire should I disconnect, Rh or Rc?

Typically, keep Rh connected for heating systems and disconnect Rc. However, this depends on your specific HVAC setup. Check your system documentation or consult an HVAC technician to determine which transformer powers which system.

Q: Why does my Nest think I have two transformers?

Your system likely has separate transformers for heating and cooling, which is common in many HVAC installations. The Nest detects this when both Rh and Rc wires are connected or when a jumper wire incorrectly bridges these terminals.

Q: Will disconnecting a wire affect my heating or cooling?

If done correctly, disconnecting the proper wire should not affect your system's operation. The Nest can typically control both heating and cooling through a single transformer connection. Test both functions after making the fix.

Abstract

Google Nest error code W5 means your thermostat has detected two transformers in your HVAC system's wiring, which can cause damage if not corrected. This happens when both Rh (heating) and Rc (cooling) wires are connected when they should be separate, or when an improper jumper wire is installed.