BOLDR HOME

MrCool Mini-Split Error Codes: Complete 2026 List

by Dua Jones April 27, 2026

MrCool mini-splits display error codes on the indoor unit's LED display panel or communicate them through the SmartHVAC app for WiFi-connected models.

MrCool's DIY and Universal series are popular for self-installation, and understanding the error codes is especially important for owners who handle their own troubleshooting. This guide covers the most common MrCool error codes for both the DIY and classic series.

Klima - Smart Home Thermostat for Mini-splits, Air Conditioners and Heatpumps

Compatible with all brands of ACs and Mini-Splits Automate Climate Management Control remotely Reduce Energy Consumption Monitor bills in realtime

Try Now

Common MrCool Error Codes

Error Code	Meaning	DIY Fix?	First Step
E1	High pressure protection	Partially	Check outdoor unit airflow; reset breaker
E2	Low pressure / refrigerant issue	No	Call EPA-certified technician — refrigerant check
E3	Outdoor fan motor fault	Partially	Clear debris from outdoor unit; call tech
E4	Compressor overload / overheating protection	Partially	Clear outdoor unit airflow; reset; call tech if recurring
E5	Outdoor unit overcurrent protection	No	Reset breaker; call tech if recurring
E6	Communication error (indoor to outdoor)	Partially	Reset breaker; check and reseat communication wire
F1	Indoor intake temperature sensor fault	No	Reset; call tech if recurring — thermistor
F2	Indoor coil temperature sensor fault	No	Call technician — thermistor replacement
P1 / PL	Freeze protection — coil too cold	Yes	Clean filter; let coil thaw 2–3 hrs; restart
dF / DF	Defrost cycle — normal in heating mode	N/A — normal	Wait 3–10 minutes; heating resumes automatically
CF	Filter cleaning reminder	Yes	Clean filter; reset indicator on remote

MrCool DIY Series — App Error Codes

MrCool DIY series units connected via the SmartHVAC app also display error codes within the app interface. If the app shows an error, it will typically also display a brief description and a recommended action. The app log can be helpful for identifying intermittent faults that cleared before you could read the code on the display.

Frequently Asked Questions

My MrCool shows E6 right after installation — what's wrong?

E6 (communication error) appearing immediately after a new DIY installation almost always means the communication wire between the indoor and outdoor units is not fully connected. Open both the indoor and outdoor unit panels and verify that the communication wire (typically labeled "1, 2, 3" or similar) is firmly seated in the correct terminal at both ends. A single loose terminal is enough to trigger E6.

My MrCool DIY shows E2 — can I fix it myself?

E2 (low pressure protection) typically indicates insufficient refrigerant charge. MrCool DIY units come pre-charged with refrigerant — if E2 appears on a new installation, the line set connections may not have been properly torqued, allowing refrigerant to escape. A qualified EPA-certified technician must check the connections, locate any leak, and recharge the system.