When a MrCool mini split stops on a fault, the indoor unit shows a code instead of the temperature, flashes its lights, or reports the code in the MRCOOL SmartHVAC app. This guide lists the MrCool mini split error codes, what each one means, which displays aren’t faults at all, how to reset the system and what the fixes usually cost.
The definitions come from MrCool’s own support center, which publishes its code tables by generation rather than by product line, and from MrCool’s troubleshooting guides and warranty documents. They cover the DIY, Advantage, Olympus, E Star and Universal lines.
Table of Contents
First, which generation do you have?
- Generations 1 to 3 show two-character codes, such as E1, F0 or P4.
- 4th and 5th Generation units show four-character codes, such as EL-01 or PC-04.
Many codes have an equivalent in each system, and MrCool’s own articles name them together: E1 and EL-01 are both a communication error, P4 and PC-04 are both a compressor drive error, and EC and EL-0C both point to refrigerant. Your generation is printed on the unit’s label and in your manual.
Where to find the code
- The indoor display shows it on most wall units.
- Flashing lights on units without a display. Count the flashes and compare them with your manual. On 4th Gen E Star units, for example, EH 00 flashes once, EL 01 twice and EH 02 three times.
- The SmartHVAC app on Wi-Fi units.
- If the display is switched off, MrCool says that on some models you can turn the unit off with the remote and hold the LED or TEMP button for about 5 to 10 seconds to show the code. The button name varies by model.
Displays that aren’t faults
- dF means the unit is defrosting, which MrCool calls normal. If it happens very often, clear snow and obstructions around the outdoor unit or add a wind and snow shield.
- cF is anti-cold-air: the indoor fan waits in heat mode until the coil is warm, so it doesn’t blow cold air.
- FC is forced cooling, a service mode.
- “–“ on a multi-zone system means two indoor units are asking for opposite modes, such as one heating and one cooling.
- P3 or PC-0L is a protective shutdown when it’s colder than about -13°F outside. Wind chill or moisture can trigger it at slightly warmer temperatures. It clears when the temperature rises.
MrCool error codes, Generations 1 to 3
| Code | What it means |
|---|---|
| E0 | Indoor memory (EEPROM) error |
| E1 | Indoor and outdoor units not communicating |
| E2 | Zero-crossing detection error (power signal) |
| E3 | Indoor fan speed out of control |
| E4 | Room temperature sensor fault |
| E5 | Indoor coil sensor fault |
| E6 | Loose temperature sensor |
| EC | Refrigerant leak detected |
| F0 | Compressor overcurrent protection |
| F1 | Outdoor air temperature sensor fault |
| F2 | Outdoor coil sensor fault |
| F3 | Discharge temperature sensor fault |
| F4 | Outdoor memory (EEPROM) error |
| F5 | Outdoor fan speed out of control |
| P0 | Inverter module (IPM) fault or overcurrent |
| P1 | Voltage too high or too low |
| P2 | Compressor top too hot |
| P3 | Outdoor temperature too low |
| P4 | Compressor drive error |
| P6 | Refrigerant charge too high or too low |
| P7 | Smart kit (Wi-Fi module) not installed |
Multi-zone outdoor units use different meanings
On Gen 1 to 3 multi-zone systems, the outdoor unit has its own list, and the same codes mean something else: E2 is a communication fault, E5 is voltage protection, P1 is high pressure and P2 is low pressure. F1 to F6 point to the coil sensor of indoor unit A to F. Always check whether a code came from the indoor or the outdoor unit.
MrCool error codes, 4th and 5th Generation
| Code | What it means |
|---|---|
| EH-00, EH-0A | Indoor memory (EEPROM) error |
| EL-01 | Indoor and outdoor units not communicating |
| EH-02 | Zero-crossing detection error |
| EH-03 | Indoor fan speed fault |
| EH-60 | Room temperature sensor (T1) fault |
| EH-61 | Indoor coil sensor (T2) fault |
| EH-0b | Indoor board and display not communicating |
| EC-51 | Outdoor memory (EEPROM) error |
| EC-52 | Outdoor coil sensor (T3) fault |
| EC-53 | Outdoor air sensor (T4) fault |
| EC-54 | Discharge temperature sensor fault |
| EC-56 | Coil outlet sensor fault |
| EC-07 | Outdoor fan speed fault |
| EL-0C | Refrigerant leak (4th Gen) or low refrigerant (5th Gen) |
| PC-00 | Inverter module (IPM) fault or overcurrent |
| PC-01 | Voltage protection |
| PC-02 | Compressor top, IPM or high-pressure protection |
| PC-03 | Low-pressure protection |
| PC-04 | Compressor drive error |
| PC-08 | Current overload protection |
| PC-40 | Main chip and driver chip not communicating |
| PC-0L | Outdoor temperature too low |
5th Generation units add refrigerant sensor codes: EH-C1 (leak detected), EH-C2 and EH-C3 (sensor alerts), EC-C1 (another zone detected a leak) and FH-CC (sensor fault). MrCool’s ducted Universal and Hyper Heat systems use the same EH, EL, EC and PC family, plus codes such as EH-0E for a high water level in the drain pan.
The Olympus ceiling cassette has its own list in which F5 to F9 and P0 to P8 mean different things, so cassette owners should use their manual.
EC and EL-0C: the refrigerant codes
MrCool lists four causes for EC or EL-0C: a low charge from a leak, service valves that weren’t fully opened during installation, loose flare connections, and, rarely, a faulty indoor pipe sensor. On 4th Gen units the system checks the indoor coil temperature shortly after the compressor starts, and shows the code and shuts down if the problem repeats three times.
For DIY systems, MrCool says owners can confirm that both service valves are fully open and that the connections are tight. Finding a leak and recharging refrigerant are jobs for a licensed technician, and MrCool lists the Advantage and Olympus lines as technician-only. If a 5th Gen unit shows EH-C1, treat it as a leak: switch the system off and call a technician.
How to reset a MrCool mini split
MrCool’s support articles recommend switching off the unit’s breaker for 15 minutes, then restoring power. The older E Star troubleshooting guide says 2 minutes, so the longer wait is the safer choice. If the same code comes back, the cause is still there, and repeated resets won’t fix it.
What you can safely check yourself
- Clean the filters. Hold each filter up to the light. If you can’t see through it, vacuum it, rinse it in lukewarm water and let it dry fully before refitting.
- Test the drain. MrCool suggests pouring one or two cups of water into the indoor unit’s drain pan to make sure it drains. Don’t use bleach.
- Clear the outdoor unit. Remove leaves, snow and ice, and with the power off, check that the fan blades turn freely. For P2 or PC-02 in hot weather, MrCool suggests shading the unit.
- Check the outdoor sensor in winter. For P3 or PC-0L, make sure the sensor isn’t covered in ice or snow.
- Write down the code before you reset anything, so the technician can see the history.
If your mini split keeps stopping and starting without a code, see our guide to heat pump short cycling. If the outdoor unit is caked in ice, see our frozen heat pump guide.
What MrCool repairs usually cost
| Repair | Likely codes | Typical cost |
|---|---|---|
| Cleaning filters, clearing the outdoor unit | P2, PC-02, frequent dF | Little or nothing if you do it |
| Diagnostic visit | Any | $60–$200 |
| Fan motor (indoor or outdoor) | E3, F5, EH-03, EC-07 | $200–$700 |
| Control board | E0, F4, EH-00, EC-51, P4, PC-04 | $150–$700 |
| Refrigerant leak repair | EC, P6, EL-0C, PC-03, EH-C1 | $300–$1,200 |
| Compressor | F0, P0, PC-00, PC-08 (once other causes are ruled out) | $650–$2,400 (up to $4,500 on some mini splits) |
Ranges come from Angi’s heat pump repair data and PickHVAC’s mini split repair cost guide (May 2026). Under warranty, you mostly pay for labor, which MrCool’s DIY warranty doesn’t cover.
Is it covered by the warranty?
| MrCool line | Parts | Compressor |
|---|---|---|
| DIY | 5 years | 7 years |
| Olympus | 5 years | 7 years |
| Advantage | 1 year | 2 years |
| Universal | 10 years (5 if not registered) | 10 years (5 if not registered) |
| Central Ducted Hyper Heat | 10 years, plus 10 years limited labor | 10 years |
Coverage starts from the original purchase date and isn’t transferable. DIY systems need no installation invoice to file a claim, but every other MrCool system needs a valid installation invoice. MrCool’s support page asks owners to register within 60 days of installation for full benefits, although the DIY 5th Gen and Olympus warranty documents say registration isn’t required. Labor and refrigerant aren’t covered on the DIY line.
Frequently asked questions
What does EC mean on a MrCool mini split?
EC on Generations 1 to 3, or EL-0C on 4th and 5th Gen, points to refrigerant: usually a leak, service valves that weren’t fully opened or loose flare connections. Leak repair and recharging need a licensed technician.
What does E1 mean on a MrCool?
E1, or EL-01 on newer units, means the indoor and outdoor units have stopped communicating. Wiring and power problems are the usual causes.
Is dF an error on a MrCool?
No. dF means the unit is defrosting its outdoor coil, which MrCool describes as normal in heating mode.
How do I reset a MrCool mini split?
Switch off its breaker for 15 minutes, as MrCool’s support articles recommend, then restore power. If the same code returns, call MrCool support or a technician.
Why does my MrCool stop working in extreme cold?
Below about -13°F outdoors, MrCool units show P3 or PC-0L and shut down to protect the compressor. They restart when it warms up.
Sources
- MrCool Support, Mini Split Systems Error Codes (July 2025)
- MrCool Support, How To Find An Error Code On A Mini Split (June 2025)
- MrCool Support, EC / EL0C refrigerant leak error (June 2025)
- MrCool Support, dF defrost display (November 2024)
- MrCool Support, cF anti-cold-air display (November 2024)
- MrCool Support, P3 / PC0L low outdoor temperature protection
- MrCool Support, Error Codes: Central Ducted System (May 2025)
- MrCool Support, filter cleaning and drain check (April 2025)
- MrCool Support, What is my Warranty Coverage? (June 2026)
- MrCool, DIY E Star 4th Generation troubleshooting and solutions guide (October 2021)
- Angi, Heat Pump Repair Cost
- PickHVAC, Mini Split Running, Service and Repair Cost (May 2026)