Mitsubishi mini-split systems are known for their reliability, but like any HVAC system, they can run into issues. When something goes wrong, your system will display an error code to help diagnose the problem. Below is a guide to the most common Mitsubishi mini-split error codes, their meanings, and possible solutions.
Common Mitsubishi Mini-Split Error Codes
1. P-Series & M-Series Indoor Unit Error Codes
| Error Code | Issue | Possible Solution |
|---|---|---|
| P1 | High-pressure issue | Check for blocked airflow around the outdoor unit. Clean filters and coils. |
| P8 | Overheating | Ensure the unit has proper ventilation and clean air filters. |
| P9 | Sensor malfunction | Inspect temperature sensors and wiring connections. |
| E0 | Indoor/Outdoor unit communication error | Reset the system by turning it off for 10 minutes. Check wiring connections. |
| E6 | Malfunction in indoor unit fan motor | Check for obstructions in the fan and ensure it's spinning freely. |
| E9 | Drain pump failure | Inspect the drain pump and line for clogs or obstructions. |
| U4 | Miscommunication between indoor and outdoor unit | Inspect wiring connections and reset power. |
| U8 | Outdoor unit fan motor failure | Check the fan motor for debris and verify it is functioning properly. |
2. Outdoor Unit Error Codes
| Error Code | Issue | Possible Solution |
|---|---|---|
| P5 | Overload protection activated | Ensure the outdoor unit has proper airflow and isn’t overheating. |
| P6 | High discharge temperature | Check refrigerant levels and clean condenser coils. |
| P7 | Outdoor unit overheating | Inspect fan motor operation and clean coils. |
| E1 | Outdoor PCB failure | Requires a technician to diagnose and repair. |
| E5 | Compressor overload | Inspect electrical connections and refrigerant levels. |
| E7 | Outdoor unit thermistor issue | Check sensor wiring and replace if necessary. |
How to Reset a Mitsubishi Mini-Split System
If your unit displays an error code, try these basic troubleshooting steps before calling for service:
-
Turn Off the Power:
- Locate the power switch or breaker for your unit. Turn it off and wait 10 minutes.
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Check for Obstructions:
- Ensure filters, vents, and outdoor coils are clean.
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Restart the System:
- Turn the power back on and see if the error clears.
-
Inspect for Visible Damage:
- Check wiring, sensors, and drains for any visible issues.
When to Call a Professional
If the error code doesn’t clear after resetting or if you’re dealing with refrigerant leaks, electrical problems, or compressor failures, it's best to call an HVAC professional like McCorry Comfort for proper diagnosis and repair.
Mitsubishi mini-split systems are great for energy-efficient heating and cooling, but keeping them well-maintained will help prevent common issues and extend their lifespan. If you're in Philadelphia and need service, McCorry Comfort can help!