5 Signs Your Car's Aircon Needs Regassing Before Summer

A car aircon regas fixes weak cooling only when low refrigerant is the real cause. The usual clues are vents that blow cool rather than cold air, a cabin that's slow to cool, and a system that worked last summer but struggles this one. Melbourne's first hot week is when a system that's running low usually shows it.

A car aircon regas is a service that removes the old refrigerant, checks that the system holds pressure, and recharges it to the quantity the car's manufacturer specifies. Refrigerant is the gas the system circulates to carry heat out of the cabin. A sealed system in good condition shouldn't need regular top-ups, so a car that needs one every season almost always has a leak. Common spots are a hose fitting, a seal or a stone-damaged condenser.

1. Airflow that's cool, but not cold

Air that's cooler than outside but not as cold as it used to be is usually the first sign of refrigerant loss. For example, a car that cooled quickly last January but needs the fan on maximum this January is showing that slow loss. Small leaks develop slowly at hose fittings, O-rings and seals. Stones can also damage the condenser at the front of the car. By the time you notice weaker cooling, the system has often been running low for a while.

Here's a quick check you can do yourself. With the engine running and the AC on, listen for a click from the engine bay and a small change in idle as the compressor engages. If that never happens, the system may be too low on refrigerant for the compressor to switch on, or there's an electrical fault. Either way, it needs testing.

2. It takes longer to cool the cabin down

A healthy system brings a hot cabin to a comfortable temperature within the first few minutes of driving. If you're waiting much longer, or running the fan on maximum just to get by, the system is probably short of refrigerant pressure.

Check the obvious first. Recirculate mode cools a hot cabin faster than drawing in outside air on a 40-degree day. Leaves and bugs packed into the condenser in front of the radiator also cut cooling, especially in slow traffic with little airflow through the grille.

3. Unusual noise when the AC is running

A rattle, squeal or grinding sound that only happens with the AC on usually points to the compressor, its clutch or the belt that drives it. Don't ignore it. The compressor's oil travels around the system with the refrigerant. So a compressor that has run low on refrigerant can also be short of oil. The damage gets more expensive the longer it goes on.

On many cars the same belt drives other engine parts too. If a noise starts, switch the AC off and book a check rather than driving around with it.

4. A musty smell through the vents

A musty smell is usually a blocked or dirty cabin filter, or moisture and debris around it, rather than a refrigerant problem. Check it during an aircon service anyway. Weak airflow often gets blamed on "low gas" when the real cause is an old filter. A clogged filter cuts the air reaching you. Even a fully charged system then feels weak.

Some water dripping under the car on a hot day is normal: it's condensation draining from the evaporator. A smell together with damp carpet on the passenger side is different, and can mean the drain is blocked.

5. It worked fine last summer, but not this one

Aircon systems can lose a little refrigerant over time even with no obvious fault, so a slow drop-off over a couple of years isn't unusual. A big drop in one year is different. A sealed system in good condition shouldn't need regular top-ups, so a car that needs one every season almost always has a leak that should be found.

There's one more reason not to wait for the heat. Your aircon also dries the air that clears a fogged windscreen, so a weak system makes wet winter mornings harder too.

Will a regas alone fix it?

Not if there's a leak. Topping up refrigerant without finding out why it's low puts you back in the same spot next year, or sooner. A proper car aircon regas tests system pressure, checks the compressor and airflow, and looks for the source of any loss. The old refrigerant is then removed, the system is checked to make sure it holds, and it's recharged to the manufacturer's specified quantity. That's the difference between a repair that lasts and one that only delays the same problem.

Refrigerant rules worth knowing

Car aircon gas is covered by national rules. The Australian Government's environment department says it's illegal to release regulated refrigerants into the air, and that only licensed technicians can handle them. The Australian Refrigeration Council adds that anyone whose work risks releasing fluorocarbon refrigerant must hold a Refrigerant Handling Licence. Handling it without one is an offence. That's why a DIY top-up isn't a sensible fix for a leaking system.

The type of refrigerant matters too. R-1234yf is the refrigerant many newer cars use instead of the older R-134a. The Council's guidance on prohibited charging says a system designed for R-1234yf can't be recharged with R-134a. The correct type and quantity are usually shown on a label under the bonnet.

Before you book

Note when the problem happens: all the time, only in traffic, only on very hot days, or only after a long drive. If the engine temperature gauge is climbing as well, the fault may be in the cooling system rather than the aircon. Our engine and cooling system repairs cover radiators, hoses and water pumps. If your car is also due for its scheduled service, you can have both done in one visit with a logbook service.

Common questions

How often does a car aircon need a regas?

A sealed system in good condition shouldn't need regular regassing. It can lose a little refrigerant over a few years, but needing a top-up every summer almost always means there's a leak. Have the leak found and fixed first, or you'll be paying for the same regas again next year.

Can I regas my car aircon myself?

It isn't a sensible fix. The Australian Refrigeration Council says anyone working on air conditioning equipment in a way that risks releasing fluorocarbon refrigerant needs a Refrigerant Handling Licence. A top-up also doesn't find the leak, and newer cars using R-1234yf can't be recharged with R-134a.

Is water dripping under my car normal when the AC is on?

Yes, a little water under the car on a hot day is normal. It's condensation draining from the evaporator. If you notice a musty smell and damp carpet on the passenger side as well, the drain may be blocked and is worth checking.

If your car's aircon isn't blowing as cold as it should, our air conditioning service in Dandenong covers diagnostics, leak finding and regassing, done properly instead of just topped up. Book a service before the weather turns, or call us on 03 8774 5785.