MRCOOL air conditioner EH 0A error code: indoor unit eeprom (control board memory) error
Also shown as EH 00, E0
- Urgency
- Medium
- Who can fix it
- Technician job
- Time
- About 20 min
- Repair cost
- $200–$650
What the EH 0A code means
EH 0A on a MRCOOL mini-split means the indoor unit's control board cannot read its EEPROM, the memory chip that holds the unit's settings. Gen 4 and Gen 5 units show EH 00 or EH 0A, and Gen 1 to 3 units show E0. A power reset sometimes clears it; if not, the board needs service.
The EEPROM is a small memory chip on the control board. It holds settings the board needs at start-up, such as the unit's model data. If the board cannot read it, the unit will not run.
A single EH 0A after a storm or outage is often a glitch that a reset clears. If it keeps coming back, the board itself is the likely fault.
Common causes
Listed from most to least common.
- Brief power glitch, surge or brownout corrupting the board's memory
- Supply voltage outside the normal range
- Loose wire or plug on the indoor control board
- Failed indoor control board
How to fix the EH 0A code
Unplug the air conditioner or switch it off at the breaker before removing any panel or filter.
Step 1: Power cycle the unit
Turn off the breaker and outdoor disconnect for 15 minutes, then turn them back on. MRCOOL says this reset may clear the code.
Step 2: Watch for power problems
Note whether lights dim or other equipment resets when the AC starts. Voltage problems can trigger memory errors, and an electrician should check the supply.
Step 3: Book a repair if it returns
If EH 0A comes back, MRCOOL's next steps are a voltage check and a look at the indoor board for loose wires or burn marks. Then the board may need replacing.
How to reset the MRCOOL air conditioner
- Turn the mini-split off with the remote.
- Switch off the breaker for the system and the outdoor disconnect switch. MRCOOL suggests leaving the power off for 15 minutes so the boards fully reset.
- Restore power and turn the unit back on. The compressor normally waits about 3 minutes before starting, so give it time before judging.
- If the same code comes back straight away, the fault is still there. Work through the fix steps above, or call a technician.
When to call a technician
If the code returns after a 15-minute reset, a technician should check the voltage and inspect the indoor control board. Opening the air handler exposes live wiring, so leave it to someone trained.
A typical repair for this code costs $200–$650 in the US, including parts and labor. Prices vary by area and model.
Models this applies to
- DIY Series ductless mini-splits (Gen 1 to 5), single-zone and multi-zone
- Advantage Series mini-splits
- Olympus Series mini-splits
- EZ-PRO mini-splits
Codes can differ slightly between models. Your owner's manual is the final word and is available from MRCOOL support.
Frequently asked questions
›What is the difference between EH 00 and EH 0A?
MRCOOL lists both as indoor unit EEPROM faults. The fix is the same: reset the power once, then have the indoor board checked if it returns.
›Is EH 0A covered by warranty?
An indoor control board is a part, so it may be covered if the unit is within its parts warranty. Labor usually is not. Contact MRCOOL support with your model and serial number.
›Can I replace the indoor board myself?
MRCOOL publishes a board replacement guide, but it involves opening the air handler and handling wiring. If you are not comfortable with that, hire a technician.