Mitsubishi Air Conditioner Error UA

⚡ Quick Answer: The Mitsubishi Air Conditioner UA error code signifies a communication failure between the indoor and outdoor units, often triggered by compressor the... ✅ DIY Fixable

What Does Error UA Mean?

The Mitsubishi Air Conditioner UA error code signifies a communication failure between the indoor and outdoor units, often triggered by compressor thermal relay operation or overcurrent protection activation. This results in the unit shutting down unexpectedly, flashing the error code, and failing to provide normal cooling or heating. Addressing this issue may require a reset, but persistent problems could indicate deeper electrical or compressor issues that need professional inspection.

Common Symptoms:

  • Air conditioner shuts down and displays UA indicating activation of a protective device
  • Unit may stop mid‑operation without normal cooling/heating

Possible Causes

  • Compressor thermal relay or overcurrent protection has tripped (medium)

How to Fix Error UA

DIY Fix Basic checks and reset

  1. Turn off the air conditioner from the main power source.
  2. Wait several minutes to allow internal protection circuits to reset.
  3. Ensure that air intake and exhaust are not blocked and filters are clean.
  4. Turn the unit back on to see if the UA error clears.

Technician Only Inspect compressor and electrical protection circuits

  1. Measure compressor current draw and compare against specification.
  2. Inspect and test the thermal/overcurrent relay (51c) and associated wiring.
  3. Check for underlying causes of overcurrent such as low refrigerant charge, high head pressure, or mechanical binding in the compressor.
  4. Test related sensors and control board outputs to confirm proper operation.

Parts needed: Compressor thermal/overcurrent relay, Compressor unit, Electrical wiring and connectors, Control board if related outputs are faulty

🛑 When to Call a Pro:
  • If the UA error persists after basic reset and visual checks.
  • If there are signs of electrical burning, noise from compressor, or refrigerant leaks.

Next step

Choose the next step for UA

Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.

Based on diagnostic data

Most relevant component to inspect

Compressor

Compresses refrigerant within the sealed cooling system and requires specialized service equipment.

Typical part-only price
$180 - $600
DIY difficulty
Hard
Estimated time
120-240 mins
Where can I find the model number?

Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.

Find a part that fits my model

Verify the complete model and part number on the retailer's compatibility page before ordering.

Other parts options

Check related components first; use model search as a fallback.

Possible related component

HVAC Control Board

Controls fan, compressor, sensor, and communication functions in the HVAC unit.

$90 - $320 · Hard · 45-120 mins

Check fit & price
Model number required

Model-compatible Air Conditioner parts

Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.

Find a part that fits my model

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Optional routine care

Maintenance supplies

These products support cleaning or routine upkeep. They are separate from the possible repair components above and are not claimed to fix this error code or symptom.

Maintenance supply

Air Conditioner Fin Cleaner

For routine cleaning of accessible coil fins when permitted by the manufacturer. Disconnect power and follow product and appliance instructions.

View maintenance supply
Maintenance supply

Model-Compatible Washable AC Filter

A reusable filter option only where the appliance supports one. Match the full model, dimensions, and filter specification.

Compatibility check required: use the complete appliance model and compare the existing filter, bag, or specification before ordering.

Find one that fits my model

Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. Recommendations are based on routine-care relevance, not commission rate.

Technical Specifications

wattage N/A
component Communication Cable
resistance N/A
part_number Mitsubishi 9346B123
voltage_rating 220V AC

Common Questions

What does UA error mean on Mitsubishi Air Conditioner?

The UA error indicates a communication failure between the indoor and outdoor units, often linked to compressor protection issues.

Can I fix Mitsubishi Air Conditioner UA error myself?

Yes, you can perform basic checks and resets, including turning off the power, waiting, and ensuring air filters are clean.

How much does it cost to fix UA error?

The estimated repair cost ranges from ¥15,000 to ¥60,000+, depending on labor and parts.

When should I call a technician for UA?

Call a technician if the UA error persists after resets or if you notice electrical burning, strange noises, or refrigerant leaks.

Data last verified: 2026-07-22

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