An aircon not cooling in Cape Town is the most common call-out of the summer. The unit runs, the fan blows, and the air coming out is somewhere between mild and warm.
The causes below all produce that same symptom at prices ranging from nothing to a new system. Nobody can tell you which one you have without measuring, but knowing the list makes the quotes you receive much easier to read.
Send the brand, the age, whether the outdoor unit is running and any error code showing. That is enough to price fault finding.
Get Repair QuotesCheck These First
- Mode. Cooling, not fan, dry or auto. It is a genuinely common cause and it costs nothing to rule out.
- Set point. Below room temperature, not 24 °C on a 24 °C afternoon.
- Filters. Pull them out and look. If light does not pass through, that is very likely your answer.
- The outdoor unit. Is the fan spinning and is air coming out warm? A silent condenser narrows things considerably.
- Airflow around the condenser. Bins, boxes, creeper or a newly built wall too close to it.
- Doors and windows. Especially on an open-plan space with a stairwell.
Common Causes, and What Each Costs
| Cause | What you would notice | Indicative repair |
|---|---|---|
| Dirty filters or evaporator coil | Weak airflow, gradual decline, sometimes icing | R650 – R2,800 (clean) |
| Dirty condenser coil outside | Outdoor unit hot, cooling fades on hot days | R650 – R1,500 |
| Low refrigerant from a leak | Slow decline over a season, icing on the thin pipe | R2,500 – R6,500 |
| Failed capacitor | Compressor hums but will not start, fan may still run | R850 – R2,200 |
| Contactor or relay | Outdoor unit does not engage at all | R900 – R2,200 |
| Outdoor fan motor failed | Compressor runs, condenser fan still, trips out after a while | R2,200 – R5,500 |
| Sensor or thermistor fault | Unit cycles oddly, or thinks the room is already cold | R650 – R1,800 |
| Control board fault | Erratic behaviour, error codes, no response to commands | R2,500 – R7,500 |
| Reversing valve stuck | Blows warm in cooling mode on a reverse-cycle unit | R3,500 – R9,000 |
| Compressor failure | No cooling at all, sometimes a trip on start | R6,500 – R18,000 |
| Unit undersized for the room | Runs constantly, never quite gets there, worst on hot days | Not a repair |
Undersizing gets misdiagnosed as a fault every summer. If the unit has never coped on a hot afternoon since the day it was installed, nothing is broken. That is a sizing problem, and the fix is a larger unit or a second one.
Aircon Blowing Warm Air
Warm rather than mild usually means the refrigerant circuit is not working at all: the compressor is not running, or the charge is very low, or a reverse-cycle unit is stuck in heating. Check whether the outdoor unit is running. If it is completely silent, the fault is almost certainly electrical — capacitor, contactor, or supply — and that is the cheaper end of the list.
Aircon Icing Up
Ice on the indoor coil or on the thin copper pipe outside means the coil is running colder than it should. Two usual causes: airflow so restricted that the coil cannot pick up heat, or refrigerant so low that pressure has dropped too far. Switch the unit off and let it thaw fully before anyone works on it, and do not chip at it.
Aircon Keeps Switching Off
Short cycling points at the unit protecting itself. High pressure from a blocked condenser, low pressure from lost charge, an overheating compressor, or a control fault. It is worth reporting how long it runs before it stops — a few minutes and half an hour point at different things.
Describe the symptom once and compare fault-finding quotes from technicians covering your suburb.
Compare Repair QuotesWhat Fault Finding Costs
| Item | Indicative range | Notes |
|---|---|---|
| Call-out and diagnosis | R450 – R950 | Frequently credited if the repair proceeds |
| Pressure and performance test | R650 – R1,800 | Where a leak is suspected |
| After-hours attendance | +R500 – R1,500 | Added to the job price |
Indicative Cape Town ranges, not a quotation. Ask whether the call-out is credited against the repair, and ask what was measured rather than what was assumed.
Frequently Asked Questions
Why is my aircon running but not cooling?
The most common causes are restricted airflow from dirty filters or coils, low refrigerant from a leak, and a failed capacitor stopping the compressor. All three look identical at the vent, so pressures and current draw have to be measured.
Why is my aircon blowing warm air?
Usually the refrigerant circuit is not running. Check whether the outdoor unit is operating. If it is silent, the fault is most likely electrical and at the cheaper end. If it is running and the air is still warm, low charge or a compressor issue is more likely.
Why is my aircon icing up?
The coil is getting colder than it should, either because airflow is restricted or because the refrigerant charge is low. Switch it off and let it thaw completely before it is worked on.
My aircon cools at night but not in the afternoon. Why?
That pattern points at the condenser struggling to reject heat: a fouled coil, poor airflow around the outdoor unit, or a unit that is marginally undersized for the room's peak load.
Is it the gas?
Sometimes, but it is assumed far more often than it is true. Refrigerant does not get used up, so a genuinely low charge means a leak. Insist that the charge is measured, not guessed, before any gas is added.
Fault finding and repairs are quoted through Aircon Installers Cape Town alongside servicing, regas and replacement.
Related Aircon Services
Aircon Installers Cape Town is a free quote-matching service. We do not install, repair or service air conditioners ourselves. Every quote comes from a LEADERR APPROVED local contractor, and your contract is with the business you appoint. Assess each quote on its own merits before appointing anyone.
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