Mitsubishi Air Conditioner Error UB

⚡ Quick Answer: The Mitsubishi Air Conditioner UB error code indicates a communication failure between the indoor and outdoor units, often leading to a blinking displ... ✅ DIY Fixable

What Does Error UB Mean?

The Mitsubishi Air Conditioner UB error code indicates a communication failure between the indoor and outdoor units, often leading to a blinking display and a lack of cooling. This issue may be caused by a blown T-phase fuse or circuit protection trip, resulting in the unit ceasing operation. To address this, a basic safety check and power cycle can be performed, or further inspection of the internal fuse and wiring may be necessary.

Common Symptoms:

  • Air conditioner displays UB error code on digital display or via lamp blink pattern
  • Unit may stop operating when error code appears

Possible Causes

  • T‑phase fuse blown or circuit protection trip (low)

How to Fix Error UB

DIY Fix Basic safety check and power cycle

  1. Turn off the air conditioner and unplug it from power for a few minutes
  2. Check that the circuit breaker for the air conditioner in your home electrical panel has not tripped
  3. Ensure that power is restored and then attempt to restart the unit

Technician Only Inspect internal T‑phase fuse / power protection and wiring

  1. Disconnect power and access the unit’s electrical compartment per service manual
  2. Measure the status of the T‑phase fuse and related protective components
  3. Inspect wiring and internal power supply for signs of damage or overheating
  4. Replace blown fuse or defective components as required

Parts needed: T‑phase fuse or internal protection device, associated wiring/harness components

🛑 When to Call a Pro:
  • If you are unsure about electrical measurements or internal fuse status
  • If replacing the fuse does not clear the UB code or the unit still fails to operate properly

Next step

Choose the next step for UB

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

Check during diagnosis

Most relevant component to inspect

Wiring Harness

Connects controls, sensors, motors, and other electrical components inside the appliance.

Typical part-only price
$20 - $120
DIY difficulty
Medium
Estimated time
30-90 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.

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 Control Board
resistance N/A
part_number Mitsubishi 938A226H01
voltage_rating 230V AC

Common Questions

What does UB error mean on Mitsubishi Air Conditioner?

The UB error indicates a communication failure between indoor and outdoor units, often leading to a blinking display and lack of cooling.

Can I fix Mitsubishi Air Conditioner UB error myself?

Yes, you can perform a basic safety check and power cycle. Turn off the unit, unplug it, and check the circuit breaker.

How much does it cost to fix UB error?

The estimated repair cost for the UB error is between ¥5,000 and ¥25,000, depending on parts and labor.

When should I call a technician for UB?

Call a technician if you're unsure about electrical measurements, or if replacing the fuse does not clear the UB code.

Data last verified: 2026-07-22

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