Before you call, work through four quick checks — power and breaker, remote batteries, mode and timer, and a reset. Many unresponsive units come back with one of these; here’s the checklist and when it needs a technician.
7 min read FreshDuct Melbourne Melbourne, Victoria
Before you call, work through four quick checks — power and breaker, remote batteries, mode and timer, and a reset. Many unresponsive units come back with one of these; here’s the checklist and when it needs a technician.
Often SimplePower, remote or mode setting
Check FirstBefore calling a technician
Then ServiceIf basics don’t fix it
Many “won’t turn on” cases come down to power (isolator/breaker), remote batteries, or a mode/timer setting. Work through these four checks first — if the unit still won’t start, it needs a technician.
Start With Power
Before anything else, confirm the unit has power. Check the isolator switch on the wall near the unit is on, and look at your switchboard for a tripped circuit breaker — reset it if it has tripped. If the breaker trips again immediately, stop and call an electrician or technician, as that indicates a fault. A surprising number of “dead” split systems are simply switched off at the isolator or have a tripped breaker (see the steps above).
Check the Remote
The remote is the next suspect. Replace the batteries with fresh ones — weak batteries are a very common cause of an unresponsive system. Check the remote’s display is working, and that you’re pointing it at the indoor unit’s receiver. If the unit responds to the manual on/off button on the indoor unit but not the remote, the remote (or its batteries) is the problem, not the system.
Mode and Settings
A system that’s “on” but doing nothing is often a settings issue. Make sure it’s set to the right mode (Cool or Heat, not Fan or Dry) and a temperature that actually calls for it — set to cool at 18°C on a warm day, or heat at 24°C on a cold one. Cancel any active timer or sleep setting that might be holding it off. These settings catch people out, especially with seasonal changeover.
Try a Reset
If power, remote and settings all check out, try a reset: turn the system off at the wall isolator for about a minute, then back on, and try again. This clears minor electronic glitches. If the unit still won’t start after a reset, the issue is internal — a control board, capacitor, sensor or wiring fault — and needs a technician to diagnose.
When to Call
Call a technician if the unit won’t start after these checks, if the breaker trips repeatedly, or if it starts then immediately stops. These point to electrical or component faults that need proper diagnosis. A technician can test the board, capacitor and electricals and identify the fault. Don’t keep resetting a breaker that keeps tripping — that’s a fault signal, not a glitch. See our not cooling guide if it runs but doesn’t cool.
Frequently Asked Questions
Why won’t my split system turn on at all?
The most common reasons are simple: no power (the wall isolator is off or the circuit breaker has tripped), dead remote batteries, or a mode/timer setting holding it off. Work through those first. If it still won’t start after checking power, fitting fresh batteries, setting the right mode and doing a reset, the cause is internal (control board, capacitor, sensor) and needs a technician.
My split system remote isn’t responding — is the unit broken?
Usually not — an unresponsive remote is most often just weak batteries. Replace them with fresh ones first. If the indoor unit responds to its manual on/off button but not the remote, the problem is the remote, not the system. If neither works, check power and try a reset. A genuinely faulty unit is less common than a flat remote battery.
My circuit breaker trips when I turn on the split system — what does that mean?
A breaker that trips when the system starts, or trips again right after you reset it, is signalling an electrical fault — not something to keep resetting. It could be a wiring, capacitor or compressor issue. Stop resetting it and call a technician (or electrician), because repeatedly resetting a breaker on a faulted circuit is unsafe. This needs proper diagnosis.
How do I reset my split system?
The simplest reset is to turn the system off at the wall isolator switch for about a minute, then turn it back on and try again. This clears minor electronic glitches. Some systems also respond to a power-off via the remote and a wait. If a reset doesn’t bring it back, the issue is internal and a reset won’t fix it — it needs servicing.
The split system was working yesterday and now won’t start — why?
A sudden failure to start is often power-related (a tripped breaker overnight, the isolator knocked off) or a flat remote battery, so check those first. It can also be a control or capacitor fault that’s just developed. Run through the power, remote, settings and reset checks — if none bring it back, a technician can quickly test the electricals to find the cause.
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