27
Jun
Air Conditioning Repair: Common Faults and When to Call an Engineer
Most air conditioning faults come down to a few causes: dirty filters, the wrong setting, a power problem, a blocked drain or a refrigerant leak. The first three you can often check yourself in ten minutes. Anything to do with the refrigerant needs an F-Gas registered engineer, because only a certified engineer is allowed to work on it.
This guide covers the common faults, what usually causes them, the checks that are safe to make first and when to call an engineer. If you'd rather hand it straight over, our air conditioning repair engineers work on all major makes in homes and businesses.
Common air conditioning faults and their likely causes
Most systems show one of a handful of symptoms when something goes wrong. This table matches each one to its usual causes and to what you can look at yourself.
| Symptom | Likely causes | What you can check |
|---|---|---|
| Blowing warm air or not cooling enough | Dirty filters, the wrong mode or set temperature, a blocked outdoor unit, low refrigerant from a leak, a failing fan or compressor | Filters, mode, set temperature, space around the outdoor unit |
| Won't switch on | Flat remote batteries, a tripped breaker or isolator, a controller or circuit board fault | Remote batteries, the breaker and the isolator switch |
| Water dripping from the indoor unit | A blocked condensate drain or pump, ice melting off the coil, a unit that isn't level | Filters. If it keeps dripping, switch off and call |
| Ice on the pipes or indoor coil | Very dirty filters starving it of air, low refrigerant, a faulty indoor fan | Filters. Run it on fan only to thaw, then call |
| Error code or flashing lights | Depends on the code: sensors, the link between the indoor and outdoor units, the drain or the refrigerant | Write down the code and the model number |
| Rattling, buzzing or grinding | A loose panel, debris in the fan, worn fan motor bearings, the compressor | Switch off. Look for debris outside only with the power off |
| Musty or bad smell | Dirty filters, mould on the coil, standing water in the drain tray | Filters. A deep clean of the coil is a service job |
| Switching on and off every few minutes | Dirty filters, a sensor fault, low refrigerant, a system too big for the room | Filters and settings |
Safe checks to make before you call an engineer
These checks need no tools and don't involve opening anything up. They fix a surprising number of call-outs.
- Check the remote or wall controller. Replace the batteries if the display is faint or blank. Make sure it's set to cool, not fan, dry or heat, and that the set temperature is below the room temperature. Check a timer or schedule isn't switching it off.
- Check the power. Look for a tripped breaker in your consumer unit or fuse board, and check the isolator switch near the outdoor unit is on. If the breaker trips again when you reset it, leave it off and call an engineer.
- Clean the filters. Switch the unit off, lift the front panel and slide the filters out. Vacuum them or rinse them in lukewarm water, let them dry fully, then refit them. Your user manual shows how for your model. In a home, every few weeks during heavy use is a good habit.
- Clear the outdoor unit. Remove leaves, bins, plants or anything stacked against it. It needs open space around it to get rid of heat.
- Give it a few minutes. Many systems wait a few minutes after being switched on before the compressor starts, to protect it. In heating mode, the outdoor unit also pauses now and then to defrost.
- Note any error code. Write down the code, the make and the model number. It helps the engineer bring the right parts.
Stop and switch off at the isolator if the breaker keeps tripping, you smell burning, you see oil on the pipework or the unit is grinding. Don't open the casing: there are live parts and pressurised refrigerant inside.
What needs an F-Gas engineer
Air conditioning doesn't use up its refrigerant. If the level is low, it has leaked out somewhere. Signs of a leak include cooling that gets gradually worse, ice on the pipes, a hissing sound and oily marks at pipe joints.
Finding and repairing a leak, and refilling the system, can only be done by an F-Gas certified engineer. We're REFCOM registered for this work. A good engineer finds and fixes the leak before refilling. Topping up without fixing it only means the refrigerant escapes again.
Other jobs for an engineer rather than a homeowner or caretaker:
- Compressor, fan motor or circuit board replacement
- Electrical faults inside the indoor or outdoor unit
- Clearing a condensate pump or a drain inside the ceiling
- Deep cleaning the indoor coil
- Diagnosing error codes that come back after a reset
Repair or replace?
Most faults are worth repairing. A blocked drain, a failed fan motor or a leaking joint is usually a straightforward fix. Replacement starts to make sense when several of these are true:
- The system is old and has needed several repairs in the last few years
- Parts for the model are no longer made, or are hard to get
- It uses an older refrigerant that can no longer be used for servicing
- The repair needed is a major one, such as a compressor on an ageing system
- It never cooled the room properly, because it was too small or in the wrong place
The cost of a repair depends on the fault, the parts and the time it takes, so we diagnose it first. We'll tell you what the repair involves and whether it's worth doing. If replacement makes more sense, we can survey the room and quote for a system sized for it.
Servicing prevents most breakdowns
Many of the faults above start small. Dirty filters lead to ice on the coil. A partly blocked drain ends up as water through the ceiling. A slow leak becomes a system that stops cooling on the hottest day of the year.
Air conditioning should be serviced at least once a year, ideally before summer. A service typically includes cleaning or replacing the filters, cleaning the indoor coil and outdoor unit, checking refrigerant pressures for leaks, clearing the condensate drain, checking electrical connections and controls, and testing the air temperatures the system produces. Systems that work hard, such as server room cooling or units in a busy shop, may need servicing more often.
Air conditioning repair for homes and businesses
In homes, we work on systems in bedrooms, home offices, living rooms and conservatories. In businesses, we look after offices, shops and server rooms, where a failed system affects staff, customers or equipment.
For businesses we offer maintenance contracts, quoted for each site, with planned visits around your opening hours and the F-Gas leak checks and records you need to keep. We also repair commercial refrigeration and heat pumps, so one team can look after all your systems. If you run a kitchen or shop, our guide to what to do when a fridge or cold room fails may also help.
Our engineers work from ATE House in Carlin How, near Saltburn-by-the-Sea, and our office in Whitby. We cover Tyne and Wear, Northumberland, County Durham, North Yorkshire and East Yorkshire, and we have more than 30 years' experience in refrigeration and air conditioning.
Book an air conditioning repair
If the safe checks haven't fixed it, or the fault involves the refrigerant, book an engineer. Have the make, the model and any error code to hand when you get in touch.
Call 01287 281014 or 07931 908711, email info@ateservices.co.uk, or see our air conditioning repair and servicing page. Our office is open Monday to Friday, 9am to 5pm.
