E13
iComfort
Safety Lockout / Excessive Fault Retries
Thermostat displays E13 and system cycles off unexpectedly due to safety lockout
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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
Repeated ignition failures reported by furnace, Repeated compressor lockouts from outdoor unit, Persistent communication errors, Over‑temperature or over‑pressure trips in connected equipment
How to Fix / Troubleshooting
Safety first: Turn off power to the furnace/air handler and outdoor unit before opening any panels. Gas and high‑voltage components can be hazardous.
- Step 1 – Note timing: Observe when E13 occurs (during heat, cool, or fan only). This helps identify which piece of equipment is locking out.
- Step 2 – Check equipment error codes: At the furnace or outdoor unit, read the onboard LED flash codes or display to determine the underlying cause (e.g., ignition failure, pressure switch open).
- Step 3 – Reset power: Turn off power to the affected unit for 5 minutes, then restore. Many lockouts will clear after a power cycle, but the root cause must still be addressed.
- Step 4 – Address root cause: Follow the equipment’s service manual to correct the underlying issue (e.g., dirty flame sensor, low refrigerant, blocked coil). This often requires a licensed HVAC technician.
- Step 5 – Clear thermostat fault: After repairs, clear E13 from the thermostat fault history and monitor operation for several cycles.
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Repair Difficulty
Professional Required
5/5
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