How do I know if my AC compressor has failed?

The unit runs but doesn’t heat or cool, trips the power, or makes loud noises from the outdoor unit. But a compressor that just hums and won’t start is often a failed capacitor or contactor — worth checking first.

Is a humming compressor always a failed compressor?

No — a hum with no start is frequently a capacitor or contactor problem, both far cheaper to replace. A technician should rule those out before condemning the compressor.

Can I replace a compressor myself?

No. It requires recovering and recharging refrigerant (ARC-licensed work by law), plus brazing and electrical work. It’s strictly for a licensed, ARC-accredited technician.

What’s the crankcase heater for?

It keeps the compressor oil warm so the compressor starts safely in cold weather. A failed one can cause hard starting and compressor wear. It’s in this category.

Are your compressors genuine Daikin?

We supply genuine Daikin compressors matched to your model’s capacity and refrigerant. Give us your model number and we’ll confirm the right one.

Daikin Compressors: Failure Signs, Causes & Replacement

Genuine Daikin air conditioner compressor — National AC Parts

The compressor is the heart of a Daikin air conditioner — it pumps the refrigerant that carries heat into or out of your home. It’s the most critical and most expensive part in the system, and also the most commonly misdiagnosed: plenty of “dead compressors” are actually a failed capacitor or contactor. This guide explains what the compressor does, the signs it’s genuinely failing, and why replacement is specialist, ARC-licensed work.

What the compressor does

The compressor pumps refrigerant around the system under pressure — that’s what makes heating and cooling possible. Daikin uses scroll and swing compressors, matched to the model’s capacity and refrigerant. When the compressor can’t pump properly, the unit runs but the air coming out isn’t hot or cold.

Signs your compressor is failing

The unit runs but doesn’t heat or cool.
The outdoor unit trips the power or the breaker.
Loud, rattling or grinding noises from the outdoor unit.
The compressor gets very hot and cuts out on overload.
The compressor won’t start at all — though this is often a capacitor or contactor, not the compressor.

Check the cheap parts first

Because a failing compressor and a failed capacitor or contactor can look identical — a hum, no start — a good technician rules out the inexpensive parts before condemning the compressor. Replacing a compressor is a major job; replacing a capacitor isn’t. It’s worth diagnosing properly.

The crankcase heater

Many Daikin outdoor units have a crankcase heater that keeps the compressor oil warm, so the compressor starts safely in cold weather. A failed crankcase heater can lead to hard starting and compressor wear, so it’s part of looking after the compressor — and you’ll find it in this category.

Safety: ARC-licensed work

Replacing a compressor means recovering and recharging refrigerant — ARC-licensed work under Australian law — along with brazing and electrical work. It is strictly a job for a licensed, ARC-accredited technician, and is not a DIY repair under any circumstances.

Genuine Daikin compressors — matched to your system

A compressor has to match the system’s capacity, refrigerant and electrical characteristics. A genuine, model-matched Daikin compressor is specified for your unit, so it integrates correctly with the controls and protection the system was designed around. We supply genuine Daikin compressors matched to your model.

How to find the right compressor

Compressors are model-specific, and Daikin parts aren’t searchable by model number online — so tell us your model. Send a photo of your Compliance Plate or give us your model number, and we’ll confirm the right genuine compressor.

Daikin Compressors FAQs

A compressor is a major repair, so getting the diagnosis and the part right matters. Browse our genuine Daikin compressors, or send your model number and we’ll match the exact part. Call 1300 904 554 or email daikin@nationalacparts.com.au.

ARC licence holder? Enter your promo code and licence number at checkout for your ARC discount on genuine Daikin spare parts.