Thermostat emits a burning smell or feels unusually hot to the touch

Safety first: Immediately turn off power to the furnace/air handler and outdoor unit at the breakers. Do not continue using a thermostat that smells like burning or is excessively hot.

Steps to troubleshoot:

• 1. Remove thermostat: After power is off, carefully remove the Emerson thermostat from the wall plate and inspect the back for burn marks or melted plastic.
• 2. Inspect wiring: Check for miswired high-voltage lines accidentally connected to the low-voltage thermostat cable, and look for signs of arcing.
• 3. Do not reuse damaged unit: If any burn damage is visible, do not reinstall or power the thermostat.
• 4. Correct wiring errors: Verify that only low-voltage (24VAC) control wires are connected to the thermostat terminals according to Emerson’s wiring diagram.
• 5. Replace thermostat: Install a new Emerson smart thermostat once wiring has been confirmed safe.

When to call a professional: Always have an HVAC technician or qualified electrician inspect the system after any overheating or burning smell to ensure there is no ongoing electrical hazard.