How often should car air conditioning be serviced?

Hella, which makes air conditioning parts, recommends an air conditioning check every 12 months and a full service every two years. Your car's own service schedule may set its own interval, so check that first. A check before summer catches a slow leak before the first hot day does.

Can an R134a car be converted to R1234yf, or the other way round?

No. The Australian Refrigeration Council advises that R134a systems should not be converted to R1234yf, and the two use different service couplers so the equipment cannot be swapped. Your car stays on the gas it was built for, as shown on its label.

Is R1234yf safe if it is mildly flammable?

Yes, in a system designed for it. It is classed A2L, mildly flammable, and European Commission research testing found no ignition of R1234yf under normal engine bay conditions. The flammability is the reason it needs dedicated, suitably rated service equipment, not a reason to worry about driving the car.

Air conditioning11 September 2026Updated 30 September 2026

Aircon Blowing Warm: Why It Died Over Winter and What a Regas Costs

Close-up of a car dashboard air vent with a chrome adjuster tab, set in a brown leather dash

Short answer

Aircon that worked in March and blows warm in spring is usually low on refrigerant. Every system loses some gas each year, and seals leak more readily when the system sits unused over winter. The fix is a leak test, then a regas with the correct gas, R134a or R1234yf, to the specified weight.

At a glance

Up to 10 percent of the refrigerant can escape each year, even from a new system, and seals left unused over winter become prone to leakage.
Your car takes either R134a or R1234yf. They are not interchangeable, and the label in the engine bay states which one and how much.
R1234yf is mildly flammable and needs its own service equipment, which is why its regas costs more.
A system that is low has leaked. It should be leak tested before it is refilled, or the new gas follows the old.
If the aircon blows warm, switch it off until it is checked. Running low on refrigerant increases the risk of compressor damage.

The first properly warm day arrives, you press the button expecting cold air, and what comes out is room temperature.

It worked fine in March. Nobody touched it. So how is it broken now?

This is the most predictable phone call of the year. Every workshop in Melbourne gets a run of them within about a fortnight of the first hot spell, from people whose air conditioning quietly stopped working months ago and who only just found out.

Why does aircon that worked in March blow warm now?

Usually because it is low on refrigerant. Every system loses some gas over the year, and it loses it faster when it sits unused through winter. By spring the charge has dropped below what the system needs to cool, and the first hot day is simply when you find out.

Two things are going on while you are not using it.

Refrigerant escapes slowly, all year round. Hella, which makes air conditioning components, puts it plainly: "Up to 10 % of the refrigerant escapes per year, even from a new air-conditioning system." The seals, hoses and connections are not perfectly gas-tight. That is why a regas is a maintenance item rather than a repair.

The seals suffer when the system sits idle. The compressor oil travels around the system with the refrigerant, and it is what keeps the seals supple. Bosch notes that "if you are not running the aircon regularly (for example in cooler weather), the seals in the system can be deprived of lubrication and become prone to leakage."

So the loss carries on over winter, at exactly the time nobody would notice.

There is a simple habit that helps. Run the air conditioning for ten minutes or so regularly through winter, even with the heater on. It keeps the oil moving round the seals. On many cars the windscreen demist setting switches the compressor on to dry the air, which does the same job.

Does my car take R134a or R1234yf?

It takes one or the other, and the label in the engine bay tells you which. R134a was the standard for decades. Since 2017, European law has required a low-impact refrigerant in every new car sold in the EU, and in practice that means R1234yf. Don't go by build year alone. Check the label.

This is where the bill gets decided, and most owners have no idea it applies to them.

European makers moved first because the law made them. The European Commission's rules applied in two steps: "From 1 January 2011, air conditioning systems in new vehicle types must be filled with a refrigerant that has a low impact on the climate", and from 1 January 2017 refrigerants with a global warming potential above 150, which rules out R134a, were banned "in all new vehicles put on the EU market". The industry body Fluorocarbons.org says almost 100% of new passenger cars sold in the EU now use R1234yf.

So a late-model European car is very likely to be on R1234yf, while an older one, or one built in the changeover years, could be either. Other makes sold in Australia switched on their own timetables.

They are not interchangeable, and that is deliberate. The Australian Refrigeration Council notes that the R1234yf circuit "is accessed using service couplers that are a different size to those of a R134a system", so the wrong equipment cannot be connected. The compressor oils differ too, and the Council advises that R134a systems "should not be converted to use R1234yf."

How to find out which one you have: open the bonnet and look for the air conditioning sticker in the engine bay, often on the underside of the bonnet or near the front of the engine bay, or on the compressor itself. Hella points to "the sticker in the engine compartment or on the compressor" for the fill quantity. It states the gas type and the exact charge weight.

	R134a	R1234yf
Typically found in	Older cars, and some later non-European models	Most European cars from the late 2010s on
Flammability	Non-flammable	A2L, mildly flammable
Service couplers	R134a size	A different size, so R134a gear cannot connect
Service equipment	R134a machine	Its own dedicated, A2L-rated machine
Compressor oil	PAG or PAO oil to the compressor maker's spec	Different PAG formulations

Why does an R1234yf regas cost more?

Because the gas itself costs more, and it needs its own equipment. R1234yf is classed as mildly flammable, so it must be handled with dedicated, suitably rated service gear. A workshop cannot run both gases through one machine, so it keeps two, and the dearer gas and machine show up on the bill.

The Australian Refrigeration Council lists the kit an R1234yf job needs: a calibrated gauge set "with dedicated R1234yf couplers", and an A2L-compliant leak detector, vacuum pump and recovery equipment. Australian radiator and air conditioning supplier Natrad describes the gas itself as more expensive than R134a.

That is the honest answer to why a regas on a late-model Audi can cost more than the same job on an older one. It is not a markup. It is a different gas and a different machine.

Why not just top up the gas?

Because if the system is low, the gas went somewhere. Air conditioning does not use up refrigerant. Every gram that has gone has leaked out, through a seal, a hose, an O ring, the condenser or the compressor shaft. Filling a leaking system means paying for gas that will be gone again.

On an R1234yf car that is an expensive way to buy a few cold weeks.

Hella's service guidance is that "before refilling the system, the system must be checked to ensure that it is leak-tight." So the job starts with a vacuum and pressure test. We pull the system down to a vacuum and watch whether it holds. If it does not, we find the leak first, usually with UV dye or an electronic sniffer, and quote the repair. If it holds, the system gets recharged with the correct gas to the exact weight the manufacturer specifies, measured by machine rather than estimated.

Can running the aircon low damage it?

Yes. Low refrigerant puts the compressor at risk, and the compressor is the most expensive part in the system. Hella notes that the normal yearly loss "reduces the cooling performance and increases the risk of damage to the compressor." A cheap problem can turn into an expensive one.

The compressor oil circulates with the refrigerant, and that oil is what lubricates the compressor. Run a struggling system for long enough and you risk the compressor failing.

When a compressor does fail, the damage rarely stays inside it. MAHLE, which makes compressors, warns that "defective compressors in particular often lead to chips in the pipes", and that when the compressor is replaced "the vehicle professional must always replace the filter dryer and expansion valve/fixed throttle." Modern condensers often cannot be flushed clean either, so they may need replacing too.

If your aircon is blowing warm, the cheapest thing you can do is turn it off until it has been looked at.

What else stops aircon blowing cold?

A blocked cabin filter, a failed condenser fan, or a climate control fault. Not every warm aircon is a gas problem, and the pattern of the symptom usually points to which one it is.

A blocked cabin filter. If the air is cold but there is barely any of it, this is the first suspect. It is a cheap part, it gets forgotten, and on a lot of European cars it also sits behind the glovebox where nobody thinks to look.

A failed condenser fan. Air conditioning that is cold on the move and warm in traffic points here. Same logic as an overheating engine, no airflow through the condenser at a standstill. Hella lists a defective condenser fan among the causes of poor cooling.

A blend door or climate control fault. Cold on one side and warm on the other, or a temperature setting the car ignores, is usually electronic rather than mechanical. That needs a scan rather than a regas.

A musty smell rather than a temperature problem. If the air is cold but the car smells musty when you first start it, that is usually growth on the evaporator, not a refrigerant issue. Hella notes that condensation forms in the evaporator's fins and "with time, bacteria, fungi, and micro-organisms settle here." It is treated differently.

Book it before the heat, not during it

Every workshop in Melbourne fills up the week the temperature first hits the mid thirties. September and October are the quiet weeks for this work, and it is the same job at the same price with a shorter wait.

If you are heading anywhere north over summer, or you have kids in the back, it is worth doing now rather than discovering the problem on the Hume in January.

We diagnose it. We fix it.

We identify the refrigerant your car takes, leak test before we fill anything, and tell you what we find before any work is authorised.

Book an air conditioning check, or read what air conditioning work covers and which European marques we work on.

Sources

Common questions

How often should car air conditioning be serviced?: Hella, which makes air conditioning parts, recommends an air conditioning check every 12 months and a full service every two years. Your car's own service schedule may set its own interval, so check that first. A check before summer catches a slow leak before the first hot day does.
Can an R134a car be converted to R1234yf, or the other way round?: No. The Australian Refrigeration Council advises that R134a systems should not be converted to R1234yf, and the two use different service couplers so the equipment cannot be swapped. Your car stays on the gas it was built for, as shown on its label.
Is R1234yf safe if it is mildly flammable?: Yes, in a system designed for it. It is classed A2L, mildly flammable, and European Commission research testing found no ignition of R1234yf under normal engine bay conditions. The flammability is the reason it needs dedicated, suitably rated service equipment, not a reason to worry about driving the car.