Thermostat displays E7 and may lock out heating or cooling

Safety first: While this is primarily a configuration issue, turn off power to the HVAC system if you will be changing wiring or system type settings.

Steps to troubleshoot:

• 1. Confirm equipment type: Identify whether your system is a heat pump or conventional furnace/AC. Check the outdoor unit model number or existing thermostat labels.
• 2. Enter installer setup: On the Emerson smart thermostat, access the installer or advanced setup menu (refer to your model manual). Review the system type, number of heat/cool stages, and fan control settings.
• 3. Correct O/B setting: For heat pumps, ensure the O/B (reversing valve) is set correctly (O for cool-energized, B for heat-energized) according to the outdoor unit manufacturer.
• 4. Match wiring to configuration: Verify that W/W1, W2, Y/Y1, Y2, G, O/B, and Aux/E wires are connected only to terminals that are enabled in the configuration.
• 5. Save and reboot: After correcting settings, save changes and allow the thermostat to reboot. E7 should clear if configuration now matches the wiring.

When to call a professional: If you are unsure of your system type or staging, have an HVAC technician verify and configure the thermostat to prevent equipment damage.