Aircon Running But Not Cold? 7 Common Causes in Malaysia
Your aircond is switched on but the room is still warm. Here are the 7 most common reasons why — and what to do about each one.
Why Is My Aircond Running But Not Cooling?
This is the most common aircond complaint in Malaysia — the unit is on, the fan is blowing, but the air is warm or barely cool. Here are the 7 most likely causes.
1. Low Refrigerant Gas
Gas leaks slowly over time. When levels drop, cooling drops dramatically. Solution: Gas top-up (R22, R410A, or R32). From RM 2.50/PSI.
2. Dirty Evaporator Coil
A heavily coated coil can't absorb heat efficiently. Solution: Chemical wash (from RM 120) or overhaul depending on severity.
3. Faulty Capacitor
The capacitor powers the compressor. A weak one means the compressor runs inefficiently. Solution: Replacement from RM 150.
4. Dirty Air Filter
A blocked filter restricts airflow across the coil. Solution: Clean or replace the filter monthly — DIY task, no tools needed.
5. Thermostat or Sensor Fault
If the thermostat misreads room temperature, the compressor shuts off too early. Solution: Sensor replacement from RM 150.
6. Outdoor Unit Blocked or Overheating
If the outdoor condenser is surrounded by walls or objects, heat can't escape and cooling efficiency drops. Solution: Clear the area around the outdoor unit.
7. Undersized Unit for the Room
A 1.0 HP unit in a 600 sq ft living room will struggle. If the unit has always been weak, the HP may simply be insufficient.
What to Do First — Free DIY Checks
Before calling a technician, do these two checks yourself. First, remove the front panel and clean the air filter under running water — a blocked filter alone can reduce cooling output by 20-30% and takes 10 minutes to fix at zero cost. Second, check that the outdoor unit fan is spinning and that there are no objects or debris blocking the airflow around it. If both of these are fine and the unit is still not cooling, the issue requires professional diagnosis.
What to Do
WhatsApp KL Renovator at +60 18-298 3573. Diagnostic fee RM 138 (waived if repair is done same visit). See: Aircond Not Cold — What to Do | Gas Recharge
How Long Does a Diagnostic Visit Take?
A full diagnostic visit to identify why your aircond is not cooling takes approximately 30–60 minutes. The technician will check gas pressure with a manifold gauge, inspect the evaporator coil, test the capacitor, verify the thermostat sensor reading, and confirm outdoor unit operation. This covers all 7 causes listed above and gives you a clear diagnosis and repair cost before any work begins. Diagnostic fee RM 138 — waived if repair is carried out on the same visit.
Definitions
Key terms in this guide, explained
Short, plain-language definitions of the terms used above — written by the technicians who do the work, not copied from a manufacturer brochure.
Refrigerant — what is it, and why can types never be mixed?
Refrigerant is the working fluid that carries heat out of your room. Malaysian homes run three types: R22 in older non-inverter units, R410A in mid-generation inverters and R32 in most units sold today. They operate at different pressures and use different compressor oils, so they can never be mixed or substituted — doing so damages the compressor and voids any warranty.
Photograph the outdoor unit nameplate before you book — it tells the technician the gas type and charge weight, and stops a wrong-gas quote.
What is the HP rating on an aircond?
HP is the informal Malaysian shorthand for cooling capacity, carried over from compressor horsepower. In practice 1.0 HP ≈ 9,000 BTU/h, 1.5 HP ≈ 12,000 BTU/h, 2.0 HP ≈ 18,000 BTU/h and 2.5 HP ≈ 24,000 BTU/h. Service, chemical wash and installation prices are all quoted against these bands, which is why the technician asks for HP before quoting.
HP is printed on the indoor unit's side label and on the outdoor nameplate — check there rather than guessing from room size.
What is inside the outdoor unit?
The outdoor unit holds the compressor, the condenser coil and the fan that blows heat away from the coil. It can only reject heat if air moves freely through the fins, so a coil packed with dust, a unit boxed into a tight service yard, or a hot wall right behind it all raise running pressure and electricity use.
Leave at least 30 cm of clear air behind the condenser and never enclose it in a sealed cabinet or grille box.
Side-by-side comparison
Chemical wash vs overhaul: how deep does each go?
Same chemicals, different depth. The dividing line is whether the indoor unit comes off the wall.
| What to compare | Chemical wash (on the wall) | Chemical overhaul (dismantled) |
|---|---|---|
| Unit removed from wall | No | Yes, dismantled into parts |
| Drain tray and casing | Flushed in place | Soaked and scrubbed separately |
| Typical trigger | Annual maintenance, mild smell | Recurring leak, heavy mould, years without service |
| Published price (1.0–1.5 HP) | RM 120 | RM 420 |
In short: If a wash was done recently and the symptom returned, paying for a second wash is throwing money at the wrong depth — go to overhaul.
Quick answer
KL Renovator's practical answer: Your aircond is switched on but the room is still warm. Here are the 7 most common reasons why — and what to do about each one.
Reader FAQs
Why Is My Aircond Running But Not Cooling?
This is the most common aircond complaint in Malaysia — the unit is on, the fan is blowing, but the air is warm or barely cool. Here are the 7 most likely causes.
How Long Does a Diagnostic Visit Take?
A full diagnostic visit to identify why your aircond is not cooling takes approximately 30–60 minutes. The technician will check gas pressure with a manifold gauge, inspect the evaporator coil, test the capacitor, verify the thermostat sensor reading, and confirm outdoor unit operation.
Reviewed by real technicians
KL Renovator's HVAC Expert Team
This article links back to the same field team that services wall-mounted, ceiling cassette and window units across KL & Selangor. Meet the 4 real technicians behind KL Renovator, see their experience, and review our service standards before you book.
