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MRCOOL DIY E Star 4th Generation Error Codes
Earlier MRCOOL generations show short codes (for example P4 instead of PC 04). Codes here are from the 4th Gen troubleshooting guide.
| Code | Meaning | What to check |
|---|---|---|
| EH 00 | Indoor unit EEPROM parameter error. | Indoor control board. |
| EL 01 | Indoor/outdoor unit communication error. | Interconnect wiring and quick-connects, power to the outdoor unit. How to fix → |
| EH 02 | Zero-crossing signal detection error (some models). | |
| EH 03 | Indoor fan speed outside the normal range. | Indoor fan motor, wheel binding, connector. |
| EH 0b | Indoor PCB / display board communication error. | Display board cable and connectors. |
| EH 60 | Indoor room temperature sensor T1 open or shorted. | Measure the sensor; check connector. How to fix → |
| EH 61 | Evaporator coil temperature sensor T2 open or shorted. | Measure the sensor; check connector. How to fix → |
| EC 07 | Outdoor fan speed outside the normal range. | Outdoor fan motor, obstruction, connector. |
| EC 51 | Outdoor unit EEPROM parameter error (some models). | |
| EC 52 | Condenser coil temperature sensor T3 open or shorted. | Measure the sensor; check connector. How to fix → |
| EC 53 | Outdoor ambient temperature sensor T4 open or shorted. | Measure the sensor; check connector. How to fix → |
| EC 54 | Compressor discharge temperature sensor TP open or shorted. | Measure the sensor; check connector. How to fix → |
| EC 56 | Evaporator coil outlet sensor T2B open or shorted (free-match indoor units). | How to fix → |
| EL 0C | Refrigerant leak detected. | Leak search, especially the quick-connect or flare joints. How to fix → |
| PC 00 | IPM malfunction or IGBT over-strong current protection. | Inverter board and compressor. How to fix → |
| PC 01 | Over-voltage or low-voltage protection. | Supply voltage under load and connections. How to fix → |
| PC 02 | IPM high temperature or high pressure protection (some models). | Outdoor airflow, dirty coil, overcharge. How to fix → |
| PC 03 | Low pressure protection (some models). | Low charge (leak), closed valve, restriction. How to fix → |
| PC 04 | Inverter compressor drive error. | Compressor wiring, inverter board. How to fix → |
| PC 08 | Current overload protection (some models). |
How to read the codes
- EH codes are indoor faults, EC codes are outdoor faults, EL codes are communication or leak detection, PC codes are protection (compressor and inverter).
- Power-cycle the unit at the breaker for several minutes; if the code returns, troubleshoot it.
Codes point to a circuit, not a part. Test before replacing boards or sensors. Inverter boards hold a dangerous charge after power-off; wait and verify DC bus voltage is gone before touching them. Refrigerant work requires EPA 608 certification.
Source: MRCOOL DIY E Star 4th Generation Troubleshooting & Solutions Guide (10-22-21). The "meaning" column follows the manufacturer's wording; "what to check" is our field summary. Always go by the label on the furnace you're working on.
Related
- Mini-split communication error troubleshooting
- Mini-split flare connections (the usual leak point)
- Look up any mini-split code
Other brands
- Daikin FTX / FVXS / FDMQ with RXL outdoor (19 Series)
- Fujitsu Halcyon / Airstage splits (indicator lamp codes)
- Mitsubishi Electric MSZ-GL / MSY-GL (failure mode recall)
- Senville AURA / LETO
- LG Single / multi-split wall units (CH codes)
- Gree Livo / All-Match with LIV outdoor (R-32)
- Pioneer Diamante / Quantum (WYT-17, WYT-20, WYT-24, WYT-25, WYT-FA)
- Lennox Mini-splits: MLB / MPC / 3PC outdoor with M22A, M33C, MWMC, MCFA/B, MFMA indoor
- ACiQ Single-zone wall mount, R-454B (ACiQ-xxWS / -xxW-BL with -xxZS / -xxZPL outdoor)
- Midea High wall ductless DLFSHB (DLFSHBH09XAK, -12XAJ, -12XAK, -18XAK, -24XAK)
- Klimaire KSIE inverter wall mount (2014–2016 models, e.g. KSIE012-H120-SW)
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