Car aircon: the parts, what cleaning means, and when it is a repair

A car aircon is a loop of refrigerant: pumped by a compressor, cooled in a condenser behind the grille, and boiled off again in an evaporator behind the dashboard, where the blower pushes cabin air across it. Every fault is one of those parts, the fan that cools the condenser, the filter in front of the blower, or the wiring that tells the compressor to run.

To be clear about who does what: AutoAgapay is a car wash and detailing crew, and does no refrigerant, compressor or electrical work. The interior detail cleans the cabin, the dashboard and the vents, and a musty smell when the aircon starts is a cabin question. Cold air is a shop question. This page is here so you know what you are asking for when you get there. If the aircon runs but the air is warm, start with car aircon not cooling.

The parts, in the order the refrigerant meets them

Compressor: Driven by the engine belt, with a clutch that engages with a click when the aircon is switched on. It pumps the refrigerant round the loop. It is the expensive part, and it is usually the one that gets damaged when the system is run low on refrigerant and oil for months.
Condenser: A thin radiator in front of the engine radiator, behind the grille. Hot refrigerant gives its heat up here to the air passing through, pushed by the road at speed and by a fan at idle. It takes stones, mud and plastic bags, and when its fins are packed with dirt the aircon cools on the highway and gives up in traffic.
Receiver drier, or accumulator: A canister that filters the refrigerant and traps moisture. It is replaced whenever the system is opened for a repair, and a shop that skips it is leaving water in the loop to turn into acid.
Expansion valve, or orifice tube: The restriction where high-pressure liquid refrigerant drops in pressure and turns cold. When it clogs or sticks, the evaporator either starves or floods, and the vents go warm or the evaporator ices up.
Evaporator: A second small radiator behind the dashboard. The refrigerant boils off inside it and the fins get cold, and the blower pushes cabin air across them. Water from the air condenses on the fins and drains under the car, which is the puddle you see after parking. The fins stay damp, which is why the smell lives here.
Blower and cabin filter: The fan that moves the air, and the pleated paper filter in front of it, usually behind the glovebox. The filter is the one consumable in the system and the first thing to check when the air is weak or dusty.

What car aircon cleaning means

Three different jobs are sold under that one phrase, and they fix three different things.

A cabin filter change: The filter sits behind the glovebox on most cars and comes out by hand. A grey, packed filter chokes the airflow and carries the dust smell. This is the one aircon job most drivers can do in the driveway, and it is the first thing to do when the air feels weak.
Evaporator cleaning: A foam or spray put through the drain tube or the blower housing to clear the mould on the cold, damp fins. It is what the musty smell on start-up needs. A shop does it on most cars, and some kits are sold for doing it at home. It does not touch the refrigerant.
Vents, ducts and the cabin: The vents brushed and wiped, the dashboard cleaned, the carpets shampooed and the cabin deodorised. This is the part of the job our interior detail covers. If the smell is in the fabric rather than in the evaporator, this is where it goes.

What none of the three does is add refrigerant or fix a compressor. If the air is clean but warm, cleaning is the wrong purchase, and the causes of warm air are on car aircon not cooling. Where a cabin smell comes from, and which smells mean a mechanic rather than a clean, is on car smells and stains.

Car aircon parts: what wears, and what you end up buying

The cabin filter. A consumable, changed at each service or sooner on dusty roads, and the cheapest fix on this page.
Refrigerant. It is not used up. If the level is low, it leaked, and a top-up without a leak test leaks out again. Ask for the test first.
Hoses, O-rings and seals. Where most slow leaks are. Oily dust on a fitting is the sign.
The condenser. Stones and corrosion open leaks at the seams, and mud packs the fins. Hosed gently from the front with the engine off, it clears; against a pressure washer the fins fold flat.
The compressor and its clutch. Noisy before it fails, often taken out by a system run low for a long time. A compressor replacement normally brings the drier and a flush with it, and both should be in the shop’s written scope.
The evaporator. Leaks slowly, behind the dashboard, and the labour is in getting to it.
The blower motor and its resistor. The fan dead, or only working on the highest speed.
Pressure switches, relays and fuses. The things that tell the compressor to run, and the first things to check when everything is dead at once.

When it is a repair, and what to ask the shop

Anything involving the refrigerant, the compressor, the condenser or the wiring is a shop job, and a searcher typing car aircon repair near me is looking for that shop. Four things to ask before leaving the car with one.

A leak test before any recharge. Refrigerant work needs gauges, a vacuum pump and a leak detector. A can from the hardware store adds gas to a leak and hides the reading the shop needs.
Which refrigerant the car takes. The label under the hood says R-134a or R-1234yf, and the two are not mixed.
The pressure readings, high side and low side, and what they mean for your car. A shop that measures will tell you; one that does not measure is guessing.
What is in the written scope of a compressor job: the drier, a flush and the oil, or only the compressor.

Book the cabin clean at your address

If the problem is the smell, the dust in the vents or a cabin that has been damp through the rains, that is the interior and exterior detail, done where the car is parked. Say in the form that the smell comes on with the aircon, and whether the car has been through a flood, because a flooded cabin is a different job and has its own page. If the problem is the cold, take the questions above to a shop.

Book an interior detail Or text the crew

Sources

Motorist (Thailand), car air conditioner not cold: low refrigerant, a clogged cabin filter, a worn compressor, a failed condenser fan, and fuses, with the checks a driver can do first in a hot climate. motorist.co.th
Christian Brothers Automotive, my car’s A/C isn’t cold: refrigerant leaks, the computer shutting the compressor off, a stuck blend door, and a failed blower fan. cbac.com