Why Is My Aircon Making A Clicking Noise?
A single click at startup or shutdown is normal. Repeated clicking during a run usually means either a louvre stalling on its travel path or a relay contact chattering inside the unit. The two patterns sound similar from the room but trace to different parts.
1. Normal Startup Or Shutdown Click
How This Works
A relay clicks when it closes or opens. On a split-system aircon, the compressor contactor, fan relay, and mode-switching relay each engage at predictable points in the operating sequence. A brief click at startup or when switching modes is the relay doing what it should: once, then quiet for the rest of the run.
How To Tell
A normal click is single and predictable. It happens at startup or shutdown, then does not repeat during the run. Unlike a louvre stall, this does not return mid-cycle. Unlike relay chatter, cooling and operating stability stay normal throughout.
- Click is brief and not constant during the run.
- Cooling behaviour remains normal.
- No vibration, smell, or error pattern appears with the click.
How We'd Confirm It
We confirm the sound timing against normal relay and mode-switching behaviour before treating it as a fault.
Do not replace any switching component before listening through a full run cycle. A single startup click is the relay working, not a fault.
2. Louvre Stall On Travel Path
How This Works
The swing louvres are driven by a small stepper motor through a plastic linkage. When the linkage wears, or when something obstructs the louvre's travel path, the motor stalls briefly and recovers. The stall produces a repeating click each time the louvre passes the same point.
How To Tell
Louvre clicks repeat at the same point in each movement cycle, like a skipping record. Unlike a normal startup click, this continues throughout the run. The clearest test is disabling the swing command: if clicking stops when the louvre motor is told to hold still, the fault is mechanical, not electrical.
- Clicking repeats at the same point in a movement cycle.
- Flap direction or movement also looks off.
- The click starts when a swing command is triggered.
How We'd Confirm It
We inspect the louvre linkage, swing motor, and fan barrel for obstructions or wear before naming a part fault.
Do not replace the relay or contactor before the swing command is tested. A mechanical louvre click is often misread as an electrical fault when the diagnostic step is skipped.
3. Relay Chatter With Unstable Operation
How This Works
A failing relay contact does not switch cleanly. Instead of a single decisive click, it chatters: opening and closing rapidly before settling, or dropping out mid-cycle. Because the relay controls compressor or fan power, the chatter comes with cooling drops or surging operation.
How To Tell
Relay chatter sounds like rapid, uneven clicking while the unit surges on and off. Unlike a louvre stall, this does not stop when the swing command is disabled. Unlike a normal startup click, the pattern continues during the run and usually comes with cooling drops, erratic fan behaviour, or both.
- Clicking repeats during unstable on-off behaviour.
- Cooling drops or operation becomes erratic at the same time.
- Buzzing, breaker issues, or other fault signs appear with the click pattern.
How We'd Confirm It
Stop repeated testing. We check relay chatter, contactor condition, and board output to isolate the switching fault.
Stop using the unit if clicking is accompanied by erratic operation. Each forced restart sends a high-current spike through already-damaged contacts, accelerating failure toward a compressor or board fault.
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