Heat Pump Not Turning On? What to Check First

If your heat pump won't respond at all, no lights, no display, nothing when you press the remote, the cause is almost always electrical rather than mechanical: a tripped breaker, an isolation switch left off, dead remote batteries, or a genuine board fault. Work through these in order before assuming the worst.

Check the isolation switch and breaker first

Every heat pump has an isolation switch, a small box mounted on the wall near the outdoor unit. If it's been switched off, either during other electrical work or by accident, the whole system goes dark. Check it's in the on position.

Next, check the circuit breaker for the heat pump circuit at the switchboard. Power surges, storms, and other appliances tripping a shared circuit are common causes of a heat pump losing power with no other explanation.

Is it the remote, or the unit?

Before assuming the unit itself has failed, rule out the remote. Dead or corroded batteries are the single most common reason a heat pump appears completely unresponsive. Replace the batteries and try again from a few metres away, since a weak signal can look identical to a dead unit.

If the unit has a physical operation button on the indoor housing, most do, usually under a small flap, try that directly. If the unit responds to the physical button but not the remote, the problem is the remote, not the system.

What a genuinely dead unit looks like

If the isolation switch is on, the breaker hasn't tripped, and the physical button gets no response either, the fault sits inside the unit. This is less common than the checks above but does happen, typically a control board fault, a wiring issue from age or pest damage, or in rare cases a burnt-out component.

If you notice a burning smell or any unusual sound alongside the unresponsiveness, switch off at the breaker and don't attempt further troubleshooting. Call a technician with that detail ready.

Brand-specific notes

Mitsubishi, Daikin, and Fujitsu remotes can all lose signal sync with the indoor unit after a power outage, appearing unresponsive when only the pairing has dropped. Re-pointing the remote directly at the receiver from close range for a few seconds usually re-establishes it. Panasonic units sometimes require a fifteen-second hold on the indoor unit's reset button after any lengthy power loss before they'll respond to a remote again.

When it needs a professional

If you've checked the isolation switch, the breaker, the batteries, and the physical button, and there's still no response, the unit needs an assessment rather than more troubleshooting at home. MiHT now carries out repair work alongside servicing, so a genuine electrical fault can often be diagnosed and fixed in the same visit rather than requiring a separate referral.

Completely separate from any of that: if you're not sure whether your system's had proper care behind it, the Home Energy Health Assessment takes three minutes and tells you where things stand.

Frequently asked questions

Why won't my heat pump turn on at all?

Almost always electrical: a tripped breaker, the isolation switch left off, or dead remote batteries. Check all three before assuming the unit has failed.

My heat pump remote isn't working but the unit has power. What's wrong?

Likely a signal or pairing issue rather than the unit itself. Replace the batteries, then try the physical button on the indoor unit to confirm whether the fault is the remote or the system.

Where is the isolation switch on a heat pump?

A small switch box mounted on the wall, usually near the outdoor unit or close to the switchboard. It cuts power to the whole system.

Can a power outage stop a heat pump from responding to the remote?

Yes. Some brands lose the pairing between the remote and the indoor unit after a power loss. Re-pointing the remote directly at the unit from close range usually restores it.

Is a heat pump that won't turn on always a repair job?

No. Most cases are a tripped breaker, an off switch, or flat batteries, all fixable without a technician. A genuine internal fault is less common.