Rheem mini‑split shows E3 and may shut down during cooling or defrost; outdoor fan may stop unexpectedly.
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Shut off the outdoor disconnect and breaker. Confirm no power at the outdoor unit before removing the service panel.
- Locate the sensor: Remove the top or side panel of the outdoor Rheem unit. Find the thermistor clipped to the condenser coil tubing.
- Check mounting: Ensure the sensor is firmly attached to the coil. Reattach with the original clip or a new clip if it has fallen off.
- Inspect wiring: Look for brittle insulation, chewed wires, or corroded connectors. Repair any visible damage and ensure the plug is fully seated on the outdoor PCB.
- Measure resistance: Disconnect the thermistor and measure resistance with a multimeter. Compare to Rheem’s specified values at ambient temperature. Replace if open, shorted, or far out of range.
- Board evaluation: If a known-good sensor still triggers E3, the outdoor control board’s sensor circuit may be defective and require replacement.
Warning: Work carefully around the condenser coil fins and refrigerant lines. Do not kink or crack tubing.
Repair Difficulty
Required Part
We may earn a commission from links on this page.