E7
Wyze
Y2 Second-Stage Cooling Circuit Fault
Thermostat displays E7 and cannot control second-stage cooling on multi-stage systems.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Y2 wire not connected at Wyze base, Y2 wire loose or missing at air handler or zone panel, Incorrect system configuration for 2-stage cooling, Open Y2 conductor in thermostat cable
How to Fix / Troubleshooting
Safety first: Turn off power to the HVAC system at the breaker.
- Verify system supports Y2: Confirm your HVAC equipment actually has a second-stage cooling terminal (Y2) on the control board or zone panel.
- Inspect Y2 at thermostat: Remove the Wyze display and ensure the Y2 wire is fully seated in the Y2 terminal.
- Check Y2 at equipment: At the air handler or zone panel, confirm the same colored wire is attached to the Y2 terminal.
- Check Wyze configuration: In the Wyze app, ensure the thermostat is set up for 2-stage cooling if your system supports it. Misconfiguration can trigger E7.
- Continuity test: With power off and Y2 disconnected at both ends, test continuity of the Y2 conductor. Replace the cable if open.
- Restore power and test: Reconnect wiring, restore power, and run the system in cooling with a large temperature differential to trigger second-stage cooling. The E7 code should clear.
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Repair Difficulty
Medium
3/5
Required Part
Thermostat Cable (Y2 Conductor)
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