E15
Atlantic
Compressor Protection or Cooling Output Fault
E15 displayed and thermostat cannot control cooling output; cooling relay locked out.
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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
Shorted cooling relay contacts, Excessive short‑cycling detected by firmware, Incorrect wiring of Y output, Internal temperature of cooling relay too high
How to Fix / Troubleshooting
Safety first: Isolate power to the HVAC system and thermostat at the breaker before working on control wiring.
- Step 1 – Observe lockout timer: Many Atlantic thermostats enforce a compressor protection delay (e.g. 3–5 minutes). Wait this period after turning cooling off before turning it back on to see if E15 clears.
- Step 2 – Check wiring: Verify that the cooling call wire (Y) is correctly connected to the thermostat and HVAC control board. Ensure there are no shorts between Y and other terminals.
- Step 3 – Inspect relay (advanced): With power off, remove the thermostat and inspect the PCB cooling relay for signs of overheating or cracking. A welded relay can cause the firmware to detect a fault.
- Step 4 – Reduce short‑cycling: Adjust minimum run‑time and minimum off‑time settings in the installer menu to prevent rapid cycling, which can trigger protection errors.
- Step 5 – Replace thermostat: If the cooling relay is physically damaged or E15 persists despite correct wiring and timing settings, replace the thermostat base or full unit.
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Repair Difficulty
Hard
4/5
Required Part
Cooling Output Relay on Main PCB
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