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

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: 2026-07-01

User Comments (0)

Share your experience or solution below.

Be the first to comment!