A soft click or whoosh when your heat pump starts up is completely normal - that's just the compressor and fan kicking in. Rattling, buzzing, grinding or hissing is your heat pump telling you something's not right, and it's worth getting looked at before a small issue turns into an expensive one.
What Noises Are Nothing to Worry About?
A gentle clicking sound when the unit starts or stops, a soft whoosh of air, and the occasional light hum while it's running are all completely normal. You might also notice a slightly louder whirring when it first kicks into a high heating or cooling mode - that's the fan and compressor adjusting, not a fault.
What Noises Should I Get Checked?
Rattling - often just a loose panel or debris in the outdoor unit, but can also mean a fan blade or component has come loose.
New buzzing or humming - can point to an electrical issue.
Grinding or screeching - usually a fan motor or bearing problem.
Hissing - can mean a refrigerant leak.
Gurgling from the pipework - can also point to a refrigerant issue.
Can I Fix It Myself?
A lot of noise complaints come down to something simple - a loose cover, leaves or debris caught in the outdoor fan, or a filter that needs a clean - and you can safely check a lot of that yourself with the power off. Anything beyond that, like an electrical fault, a refrigerant issue or a worn fan motor, is a job for us. We have our own team of electricians and a dedicated faults department who handle fault finding and repairs on heat pumps, so you're dealing with one local team from start to finish rather than being passed from one tradie to the next.
Quick Questions About Heat Pump Noises
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Not usually, but switch it off and get it looked at soon rather than waiting - sudden buzzing is often electrical.
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A bit - it's working harder, and you may hear the defrost cycle kick in on very cold days. That's different from a new, unusual noise.
After 25 years servicing heat pumps across Timaru and South Canterbury - every make and model, not just Mitsubishi Electric - I've heard just about every noise a heat pump can make, and most of them turn out to be simple. If yours doesn't sound right, give us a call on 03 684 5298 or book a service and we'll get to the bottom of it.