Power Supply Voltage Abnormality

Home Appliance Error Codes Daikin Split AC

Can you still use it? With care until repaired

Who can fix it? Needs a technician

Typical repair time 15 minutes – 3 hours

Typical cost SAR 100 to 2,500

What it means

This code appears on Daikin split, ducted and cassette air conditioners and means the board has detected an abnormal supply voltage, such as a drop, a surge or a momentary power loss, or a fault in the DC voltage circuit inside the inverter board. The unit stops the compressor to protect the electronics and tries to resume once the voltage is stable. The same code can mean something else on other brands.

Models covered: Daikin split air conditioners and Daikin ducted/cassette (SkyAir) units, which share the same error code system; the code shows on the wired remote or via the wireless remote check function.

Symptoms4

The unit stops suddenly and U2 appears, especially at peak hours.
The code repeats when other large appliances in the home switch on.
House lights sometimes dim when the unit starts.
The unit works normally at other times of day.

Possible causes5

Low or fluctuating mains voltage, especially at summer peak.
A momentary power interruption.
A loose or burnt connection at the breaker or the outdoor unit terminal block.
A supply cable that is too thin or too long, so voltage sags under load.
A fault in the capacitors or DC voltage circuit on the outdoor inverter board.

How to diagnose5

Note when the code appears: at peak times or when other appliances start points to a supply problem.
Check the unit's breaker: is it hot or showing burn marks?
A technician measures the voltage at the outdoor terminal block with the compressor running and compares it with the nameplate range.
The technician checks terminal tightness and the supply cable size.
If the supply is good and the code persists, the outdoor board's voltage circuit is checked after discharging it.

How to fix5

Fit a voltage protector rated for the unit.
Tighten or replace burnt terminals at the breaker and terminal block, and replace a damaged breaker.
Replace an undersized supply cable with the correct size.
Contact the electricity provider if low voltage affects the whole building or area.
Replace the outdoor PCB if its voltage circuit is proven faulty, then test the unit at peak time.

Repair cost

0–200

200–600

600–1,500

1,500+

In Saudi riyals; the highlighted part is the expected range for this fault.

A voltage protector or a connection repair is the cheapest and most common fix; the cost only rises if the outdoor board turns out to be the cause.

Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026

Frequently asked questions

Will a voltage protector stop U2?

A protector disconnects the unit during severe fluctuations and delays restart, which protects the board, but it cannot raise a low voltage. If the drop is constant, the supply itself must be fixed.

Why does U2 only appear in the afternoon?

At summer peak, demand in the building and area pulls the voltage down while the unit draws more current in the heat, so the fault shows up in those hours.

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This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

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