Aircon remote not working? 8 fixes to try before you call a technician

Weak batteries are behind the majority of unresponsive remotes. A remote can still light up its screen while having too little power to fire the infrared LED, so a lit display does not mean the batteries are fine.

Use a fresh pair of the same type — never mix an old battery with a new one — and check the +/- orientation against the diagram inside the compartment.

Open your phone's camera, point the tip of the remote at the lens, and press any button. If the remote is transmitting, you will see a faint purple or white flash on your screen that is invisible to the naked eye.

No flash means the remote itself is faulty. A visible flash means the remote works and the problem is at the indoor unit.

If the remote is set to Fan or Dry mode, the compressor will not run and the room will not cool — the unit looks broken but is behaving exactly as instructed.

Set it to Cool, drop the temperature to 24°C or below, and give the system a few minutes.

Most Singapore models have a lock function triggered by holding two buttons together. When active, a small padlock icon appears on the display and every other button is ignored.

Hold the same combination for three to five seconds to release it. On Mitsubishi and Daikin remotes this is usually the two arrow buttons pressed simultaneously.

Infrared needs an unobstructed path. Curtains, an open cabinet door, a tall plant, or even strong afternoon sunlight hitting the indoor unit's receiver can swallow the signal.

Stand within three metres, point directly at the display panel of the indoor unit, and try again.

Nearly every remote has a pinhole marked RESET or ACL. Press it with a straightened paperclip while the batteries are in, and the remote reboots to factory defaults.

If there is no pinhole, remove the batteries, press and hold any button for 15 seconds to drain residual charge, then reinsert them.

Switch the aircon off at the isolator or the wall switch, wait a full three minutes, then switch it back on. This clears latched fault codes in the control board and restores the receiver on a surprising number of units.

Do not skip the three-minute wait — compressors have a built-in restart delay and cutting it short can trip the unit again.

Every indoor unit has a small physical button hidden behind the front flap, usually labelled AUTO or TEST. If the unit starts and cools using that button, the aircon is healthy and the fault is confined to the remote or its receiver.

This is the single most useful diagnostic you can do — it tells us on the phone whether you need a $20 replacement remote or a technician visit.

If the manual button also does nothing, the problem is electrical: a tripped isolator, a blown fuse, a failed control PCB, or a dead transformer. That needs a technician.

• Unit dead on the manual button — likely power supply or control board
• Unit runs on the manual button but ignores the remote — faulty IR receiver on the PCB
• Remote shows no phone-camera flash — replace the remote (universal remotes work on most brands)
• Blinking timer or operation LED — the unit is reporting a fault code, note the blink pattern

A universal remote runs roughly $20–$40 and covers most Mitsubishi, Daikin, Midea, Panasonic and LG units. An original brand remote costs more but guarantees full function access.

If the IR receiver board has failed, expect a parts-and-labour repair. We quote before any work starts — no surprises.