Air Conditioning Maintenance: How to keep your AC running smoothly

Air conditioning units are becoming more and more popular in the UK, especially as the typically mild UK summers become hotter and hotter. In fact, May 2025 was the UK’s hottest ever on record with temperatures hitting 29C.

But with everything worth having in life, air conditioning requires maintenance and work to make sure it functions at its maximum potential..

This guide will help you keep your unit in tip top shape so you can avoid unexpected breakdowns, improve energy efficiency and extend your unit’s life.

Regular Air Conditioning Unit Checks You Should Do

Neglecting the maintenance or your air conditioning unit can lead to higher energy bills, subpar performance and costly repairs.

Regular cleaning, inspections and tune-ups can prevent small problems from turning into big ones. From filter changes to refrigerant checks, staying on top of your maintenance routine means your AC won’t let you down when you need it most.

Clean the Filters

One of the simplest and most effective ways to keep your air conditioning unit running smoothly is to look after your filters. Over time, filters collect dust, pet hair and other airborne particles, which can restrict airflow and reduce efficiency.

Most filters should be replaced every 1–3 months, but if you’ve got pets or allergy sufferers at home, monthly checks are a good habit. We recommend setting a calendar reminder for the start of each month. It’s a small task that makes a big difference.

Check Unit Settings

This might seem obvious, but you’d be surprised how often incorrect settings lead to poor performance. You’d also be surprised to learn just how many air conditioning units have settings that have gone awry at the hands of little children. So don’t assume that because you set the system up correctly some months ago that it’s still good now. 

When checking, make sure your unit’s temperature reflects your comfort needs and use energy saving modes to help reduce running costs.

If your system has multiple fan speed options, use the appropriate one based on the outside temperature. And don’t forget, using a programmable thermostat can automate this for you, keeping your home cool when needed without wasting energy.

Be sure to refer to your systems manual or look it up online to ensure you understand the settings you’re changing. Not all air conditioning units instructions are that clear, so if you find yourself struggling to make sense of it all then give us a call.

Keep the Coils Clean

Air conditioning units have coils both inside and outside, these are crucial for keeping your home cool. The evaporator coil inside absorbs heat, while the condenser coil outside releases it. If these coils are dirty, your system has to work harder, which drives up energy use and wear. Inside, look for dust buildup or bent fins and gently clean with a soft brush. Outside, remove leaves, grass, and grime that collect around the unit.

Check the Thermostat

The thermostat on your air conditioning unit is there to make sure it only runs when needed and keeps your home at the right temperature. Placement of it is crucial, so make sure your thermostat is not placed near direct sunlight or heat sources as this can cause incorrect readings.

Test the calibration by comparing your room’s actual temperature with what the thermostat displays. If it’s not right, a professional recalibration might be needed.

If your thermostat uses batteries then be sure to change them annually. And if you haven’t yet upgraded to a smart thermostat, it might be time. They offer remote control, scheduling, and usage insights, all great ways to save energy and stay comfortable.

Keep the Vents Dust Free and Unobscured

If your air conditioning units vents are blocked then it will have to work harder to push air around the house. Much like having clean coils, the dirtier the vents are the more wear and tear on the system there will be and the less energy efficient it is.

Furniture can actually block vents too, so check whether you are blocking vents with sofas, cabinets, or beds. Use lightweight or sheer curtains in your space that don’t cover your vents. Pet hair and dander collect quickly so vacuum around vents often and consider adding vent filters.

Have a Professional Annual Service

Even if everything seems fine, an annual service is recommended in order to catch potential problems early and keep your unit running efficiently. Custom Heat’s qualified engineers will inspect your system, clean critical components, check refrigerant levels, and make sure everything’s running safely and smoothly.

We offer servicing even if we didn’t install your system, so don’t hesitate to get in touch.

Diagnosing AC Unit Problems

Sound

Hearing grinding, squealing, or rattling? It could be a loose fan, failing motor, or something more serious. Don’t ignore strange sounds as they’re usually a sign that something’s not right. Our engineers can pinpoint the issue and fix it before it turns into a full-blown failure.

Temperature

If your system isn’t cooling as well as it used to, it might be a refrigerant leak, clogged filter, or dirty coils. Even a minor drop in cooling can signal a larger issue that needs professional attention.

Performance

If you find your system is running longer than usual or struggling to cool down the room then it’s probably best to get it checked before it worsens.

Contact us for air con servicing needs

Whether you’re trying to beat the heat during the ever increasingly hot UK  summers or hunkering down on a chilly winter night, you can rely on our engineers to help you stay comfortable any time of year. 

Being proactive is the best way to have peace of mind, so whether we install them or not, we offer routine maintenance and services for your air conditioning units.