Watch a good engineer arrive for an air conditioning service and the first few minutes look like nothing at all. They run the system, listen to it, put a hand over the indoor unit to feel the air. Long before any panel comes off, a system that is struggling has usually told them so.
What the visit involves
A proper annual service is mostly cleaning and measuring. The filters come out and get washed, because a clogged filter is behind a large share of weak air conditioning complaints. The indoor coil is checked and cleaned, the condensate drain is flushed so it cannot back up and drip down your wall, and the outdoor unit is cleared of the leaves and fluff that choke its airflow. Then the measuring: temperatures across the coil, running pressures, electrical connections tightened and tested. The engineer is comparing what the system does against what it should do, and that comparison is the service. A visit that consists of a quick wipe and an invoice has skipped the part you were paying for.
The gas top-up that should worry you
Here is the piece of practitioner knowledge worth carrying into any service visit: refrigerant does not get used up. The system is sealed, like a fridge, and the gas circulates for the life of the machine. So when someone says your system needs a top-up, what they have found is a leak. Topping up without finding the leak means paying for the same gas again next year while it escapes into the atmosphere in between, which is exactly what the F-Gas rules exist to prevent. A conscientious engineer treats low refrigerant as a fault to trace, finds the leak, repairs it, and only then recharges the system. If you are offered a top-up with no talk of leak detection, ask the obvious question: where is the old gas going?
How often, and when to book
Once a year is the sensible rhythm for a domestic system, and manufacturers commonly expect evidence of servicing to honour their longer warranties. Commercial systems that run all day want checking more often. As with installation, the clever move is timing: book the service in spring, before the first heatwave, so anything the engineer finds can be fixed while you do not yet need the cooling, and while engineers still have room in the diary.
Service and maintenance work is its own discipline, and among the 996 air conditioning companies listed on this site many lead with it rather than treating it as an afterthought to installation. Find service engineers working near you, or describe your system and get service quotes. When you book, ask one thing up front: for the checklist the visit covers. A firm that can send you one runs the kind of service worth paying for.
