An aircon that stops cooling on a 30°C afternoon is more than an inconvenience, especially in a bedroom or an office full of people. Most faults have a handful of common causes, and many are cheaper to fix than people expect, provided they're found properly.
How a repair works
- The technician examines the unit and asks what it has been doing.
- The components are tested: electrical supply, fans, sensors, gas pressures and temperatures.
- You get an estimate of the cost for your approval.
- Only then does the repair start.
Common aircon problems
Aircon not cooling
- What you notice
- The unit runs and air comes out, but the room never gets cool, or the airflow is weak.
- Usual causes
- Very dirty filters, a blocked indoor or outdoor coil, an undersized unit, low refrigerant from a leak, or a failing outdoor fan, capacitor or compressor.
- What you can check first
- Check it's set to cool and below room temperature. Rinse dusty filters, let them dry and try again. Make sure the outdoor unit is running and its coil isn't covered in leaves or dust.
Aircon blowing warm air
- What you notice
- Air from the indoor unit is room temperature or warm, even in cool mode.
- Usual causes
- The unit is set to heat, fan or auto; the outdoor unit isn't running because of a tripped supply, a failed capacitor or contactor; the compressor isn't starting; low refrigerant; or, on reverse-cycle units, a valve stuck in heating.
- What you can check first
- Check the mode and set temperature on the remote, and look at whether the outdoor fan is turning. If the indoor unit runs but the outdoor unit is silent, that's useful to mention when you call.
Aircon leaking water
- What you notice
- Water drips or runs from the indoor unit, down the wall or onto the floor.
- Usual causes
- Most often a blocked or disconnected condensate drain or a cracked drain tray. Sometimes the indoor coil has iced up (from dirty filters or low gas) and is melting, or the unit isn't level.
- What you can check first
- Switch the unit off, catch the water and dry the area. Check the filters. Look outside where the drain pipe ends: if nothing comes out while the unit is running, the drain is probably blocked.
- When to switch it off
- If water is near electrical sockets or the unit itself, switch it off at the isolator or breaker.
Aircon not switching on
- What you notice
- Nothing happens when you press the remote, or the display lights up but the unit won't start.
- Usual causes
- Flat remote batteries, a tripped breaker or an isolator switched off outside, a timer setting, a faulty receiver, or a control board damaged by a power surge.
- What you can check first
- Replace the remote batteries, check the circuit breaker and the outdoor isolator switch, and try the manual button on the indoor unit if it has one. After a power outage, wait a few minutes before trying again.
Strange noises
- What you notice
- Rattling, buzzing, grinding, squealing or a loud clunk when the unit starts or stops.
- Usual causes
- Loose panels or mounting brackets, debris in the outdoor fan, a worn fan motor bearing, a damaged fan blade, or an electrical part buzzing before it fails.
- What you can check first
- Check the outdoor unit for sticks or leaves in the fan and make sure nothing is touching the casing. Note when the noise happens: at start-up, all the time, or only in one mode.
- When to switch it off
- Grinding, burning smells or a loud bang mean switch it off and leave it off until it's been checked.
Faulty compressor
- What you notice
- The outdoor unit hums or clicks but doesn't start properly, trips the power when it tries to start, runs very hot, or runs without cooling.
- Usual causes
- The compressor is the heart of the system. Problems can come from the compressor itself, or from cheaper parts around it such as a start capacitor, contactor, wiring or a fault that has made it overheat, like a blocked coil or low gas.
- What you can check first
- Not much: compressor faults need testing with instruments. Make sure the outdoor coil is clean and clear, and note whether the power trips when the unit starts.
- When to switch it off
- If the unit trips the breaker more than once, don't keep resetting it. Leave it off until it's been tested.
Refrigerant (gas) leaks
- What you notice
- Cooling gets weaker over weeks or months, ice forms on the pipes or indoor coil, there's a hissing sound, or oily marks appear on pipe joints.
- Usual causes
- Leaks usually come from flare joints, damaged pipes, corroded coils or vibration over time.
- What you can check first
- Look for ice on the pipes at the outdoor unit or oily residue at the connections, and switch off the unit if it's icing up.
About re-gassing. An aircon is a sealed system; it doesn't use up its gas. If the gas is low, it has leaked out somewhere. Topping it up without finding the leak only buys time, and you'll pay again when it runs low. Ask for the leak to be found and repaired first, then the system vacuumed and re-gassed to the correct charge.
Error codes, tripping power and bad smells
- What you notice
- A code flashes on the display, the unit trips the circuit breaker, or there's a musty smell when it starts.
- Usual causes
- Error codes point to a sensor, board or part that has reported a fault. Tripping can be an electrical fault, damaged cable or failing compressor. Musty smells usually mean mould and dirt on the indoor coil and drain tray.
- What you can check first
- Write down the code, the brand and the model. For smells, clean the filters; if it persists, the coil and drain need a professional clean.
- When to switch it off
- Stop using a unit that keeps tripping the power until it's been checked.
Parts that can be replaced
Compressors, outdoor condenser coils, fan motors, capacitors, contactors, control boards, sensors, drain pumps and remotes can all be replaced. Whether it's worth it depends on the unit's age and the cost of the part.
Repair or replace?
Many older units run on R22, a refrigerant South Africa is phasing out, which makes their gas harder to find and more expensive. If an R22 unit needs a new compressor or a major gas repair, compare the price with a new inverter split, which will also use less electricity. The technician can price both so you can decide.
Before you call
- Check the circuit breaker, the outdoor isolator and the remote batteries
- If the filters are dusty, rinse them, let them dry and try again
- Note the brand, the rough age of the unit and any error code
- If it's tripping the power, leaking near electrics or icing up, switch it off and leave it off
To stop faults coming back, a regular aircon service usually costs less than a repair.