What each MRCOOL code means — and what to do next. Stuck? AAA Comfort Air fixes MRCOOL systems across Central NJ, often same-day.
MRCOOL ductless mini-splits are efficient and quiet, but like any system they occasionally act up. When they do, the indoor unit signals the problem so it can be pinpointed quickly — and AAA Comfort Air services MRCOOL systems across Central NJ.
The indoor unit shows a code (E = communication/board, P = protection, F = sensor) on its display or by blinking the indoor LED. The indicator is a E / P / F code on the indoor display or blinking LED.
| Code | What it means | What to do |
|---|---|---|
| E1 | Indoor–outdoor communication error | Wiring or control board — call us |
| E2 | Zero-crossing signal detection error | Call us |
| P1 | Over- / under-voltage protection | Check your power supply — call us |
| P4 | Inverter compressor drive fault | Call us |
| F1 | Outdoor ambient temperature sensor fault | Call us |
| F2 | Indoor coil temperature sensor fault | Call us |
⚠️ Codes can vary by model and control-board revision — always confirm against the label inside your unit’s access panel. For any gas, electrical, or refrigerant fault, call a licensed technician.
The indoor unit shows a code (E = communication/board, P = protection, F = sensor) on its display or by blinking the indoor LED.
You can try one power cycle at the breaker to clear a one-time fault. But if the same code returns, it’s a real fault — repeatedly resetting a gas or electrical issue can be unsafe. Call AAA Comfort Air at 609-665-3022.
AAA Comfort Air installs and repairs MRCOOL systems across Cream Ridge and Central New Jersey, with same-day and 24/7 emergency service. Call 609-665-3022.
Book online or call your local MRCOOL HVAC team — same-day & 24/7 emergency service.
