When Should You Service an Air Conditioner? A Yearly Plan and the Warranty Trap

An air conditioner sits in an odd place among household appliances: its faults only surface seasonally. Nobody notices a broken AC in November. They notice it in July — the same week every technician is fully booked.

That makes it the appliance where “call someone when it breaks” costs the most. It also has an interesting warranty trap, which I’ll come to.

The yearly plan: which job, when, by whom

The critical line is pre-season. Book in April or May and you get an appointment and can negotiate; call in July and you join a queue and accept whatever price you’re quoted.

The three things you can do yourself

1. Clean the filter. The most neglected and easiest job. A dirty filter does two things: reduces cooling and increases electricity use. Once a month, warm water, dry it fully before refitting.

2. Check the drain. If water drips from the indoor unit, it’s usually not a fault. It’s a blocked drain line. One of the things to check before calling anyone; the general list is in 6 things to do before you call a repair service.

3. Clear the outdoor unit. If the outdoor unit can’t breathe — boxed in, covered over, fins clogged with dust — the system strains and the compressor’s life shortens.

What an unserviced air conditioner actually does

Neglect shows up as three quiet symptoms long before anything breaks. It stops cooling properly. A clogged indoor filter chokes the airflow. The unit runs longer for the same temperature; the bill climbs. The owner usually decides it’s “low on gas” — when the real cause is almost always the filter. It smells. Moisture in the indoor unit breeds mould in the drain tray and on the fins. That air goes straight into the room. That’s a comfort problem and, in homes with children or allergies, a health one. It drips: a blocked condensate line pushes water back out of the indoor unit and down the wall, and a slow leak nobody notices for a couple of seasons ruins plaster and paint.

What the three have in common is that none of them stops the machine — which is exactly why they get postponed. Each one worsens a little every season, turning a job one service visit would have fixed into years of running a strained compressor.

Split, ducted and VRF: what changes

On a domestic split system, most of the maintenance is the filter and the indoor unit: you can wash the filter yourself, while the fins, tray and drain are a technician’s job. On ducted and large-room systems the filter area is bigger, so fouling looks slower but costs more — a pre-season service is harder to justify skipping on those. In commercial VRF and multi-split installations, maintenance belongs in a contract: once you’re past a handful of indoor units, remembering each one stops being realistic and tracking the service contract becomes a job in itself.

The outdoor unit is the same story on every system: keep the airflow clear, keep leaves and dust off the coil, and don’t let the fins get crushed. An outdoor unit shut inside a balcony cabinet loses efficiency for a simple reason. It re-breathes the hot air it just expelled.

🔴 The warranty trap: “low on gas”

The most common sentence in AC repair: “it’s low on gas, let’s top it up.”

Here’s what to know: refrigerant doesn’t deplete on its own in a sealed system. If it’s low, there’s a leak. Topping up without finding the leak postpones the problem by one season and burns money.

The warranty trap sits right here: unauthorised work can, depending on the manufacturer, put your cover in dispute. Having “a guy you know” top up the gas while the unit is under warranty can make a later compressor claim much harder. If the unit is in warranty, the authorised service is the first address.

What to do in the final month of cover is in 5 things to do before your warranty expires — particularly relevant for AC, because the expiry usually falls in winter when nobody is thinking about it.

Opening and closing the season: two short rituals

An air conditioner needs about five minutes of attention twice a year. At the start of the season, before the first hot spell. Take out the filter, wash it, refit it once it is fully dry. Clear leaves and dust from around the outdoor unit. Then run the unit in cooling for ten minutes and check three things. Is the air truly cold? Is water dripping from the indoor unit? Any odd noise or smell? The value of that ten-minute test is all in its timing. Run on a quiet spring day, any problem it finds gets an easy slot at off-season prices — not a two-week wait in July.

At the end of the season, rather than switching off and forgetting, run the unit in heating mode briefly to dry out the indoor coil and cut mould growth over winter (or fan-only if the unit doesn’t heat). Then take the batteries out of the remote — a leaking cell is the most common reason a perfectly good remote gets replaced every couple of years.

Install quality: the one thing servicing can’t fix

The one problem no service visit cures is a bad install, and its price gets paid again every season. The indoor unit must sit at a slight tilt — the drain works by gravity, and a level or back-tilted install makes the drainage misbehave forever. The copper line’s length and the outdoor unit’s height relative to the indoor one must stay inside the maker’s limits; past them, the system never actually breaks — it just runs at low efficiency for its whole life. And a system charged without pulling a vacuum carries moisture and air in the line that wear the compressor from the inside over the years. That’s a loss no maintenance can claw back.

Buying a new unit? Ask for two things on install day: to be shown the vacuum being pulled, and a cooling test run in front of you. Keep the invoice, the warranty certificate and the installation slip together the same day.

Why records matter here

Keeping records on an air conditioner has three concrete payoffs:

• Warranty: a claim is hard without the installation date and the invoice. The installation invoice is a separate document from the purchase invoice — you need both.
• Leak tracking: knowing “we topped it up two years ago as well” is what makes a technician look for the leak. Without records, the same gas gets refilled every year.
• Sale or moving: a documented maintenance history helps when the unit changes hands.

Duevo is built for exactly this: each device recorded with its warranty date, invoice and installation photos kept alongside, reminders before scheduled maintenance and before cover ends, and completed services logged into the history. A system that reminds you in May is what keeps you out of the July queue.

For the rest of the appliances in the house, see the appliance maintenance schedule.

Frequently Asked Questions

How many times a year does an AC need servicing? General rule: a full service once a year, before the season. Filter cleaning is your job and should be repeated every 2-4 weeks in heavy use. In dusty or heavy-duty environments, professional servicing can go to twice a year.

My AC isn’t cooling — does that mean it’s out of gas? No, and usually it isn’t. Check filter cleanliness, airflow to the outdoor unit and the settings first. If refrigerant genuinely is low, the cause is a leak; topping up without finding it is a temporary fix.

Will topping up the refrigerant myself void the warranty? Practice varies by manufacturer, but unauthorised work can put cover in dispute. If the unit is under warranty the authorised service is the right address; when in doubt, check the terms on the warranty document.