Lennox Mini Split EC52 Error Code

What EC52 means

EC52 on Lennox mini splits means the condenser coil temperature sensor T3 is in open circuit or short circuited - the outdoor coil thermistor circuit is broken or out of its allowed voltage window (below 0.06 V or above 4.94 V), so the control stops the system. One power cycle; if EC52 returns, the sensor connection, the thermistor, or the outdoor control board needs technician service.

First checks before service

This page currently documents the safe reset triage. If the code returns, use the linked source manual or a qualified technician for code-specific diagnosis.

1. 1. One-time fault event (power disturbance or transient sensor reading) common DIY

   Check: Power-cycle at the breaker/disconnect (or unplug for CPAP), restore, and run the system while watching for the code.

   Fix: If the code does not return after a full run cycle, the fault was transient — monitor, no repair needed.

2. 2. Fault persists after a clean reset occasional pro only

   Check: If the code returns immediately or every session, note the conditions (startup, heating, after rain).

   Fix: A persisting code points at the component the manual assigns to this code — that repair is technician territory.