Aircon Not Cold (Warm Air Blowing) — Causes, Fixes & Cost in KL
The aircon runs but blows warm or only slightly cool air, so the room never reaches the set temperature.
Estimated professional fix: RM 129–RM 455 depending on the cause
An aircon that runs all day but never cools the room has one of four causes, and the order of checking is fixed because the cheap ones are the common ones. First: the filter and the coil. In a hot, dusty climate a neglected unit loads up with lint and mould within weeks, the airflow starves, and the unit works harder for less cooling. Second: the refrigerant. A slow leak drops the gas charge until the system can no longer pull heat out of the room — and topping up without finding the leak just buys weeks. Third: the temperature sensor, which can read the room as colder than it is and shut the compressor off. Fourth: the compressor itself, the expensive end, which fails after years of hard work or a voltage event. The diagnosis takes 30–60 minutes on site, and the pattern of the fault — warm air versus no air versus ice on the pipes — tells a technician a lot.
Common causes
Professional solutions
Safe DIY checks first
- 1Clean the filter and run the unit for a day — if it cools noticeably better, the airflow was the cause
- 2Feel the two copper pipes at the outdoor unit: both should be warm-ish in cooling mode; one cold and one warm with ice points at low gas
- 3Check the set point against the room: a unit fighting a 35 °C room at 16 °C will never win — that is not a fault
- 4Note any frost on the pipes or a hissing note — both point at the refrigerant side and should be checked before the next season
When to call a pro
What affects the cost
A basic service starts from RM129 and fixes the warm-air cases where the coil and filter are the cause. A leak check plus gas top-up runs from RM2.50 per PSI, with the leak itself repaired first. A faulty temperature sensor is a small part in the middle of the range, and a compressor repair or replacement starts from RM1,040 — quoted only after the cheaper stages are done. We diagnose on site in 30–60 minutes and explain each finding, and the work carries the standard warranty.
How to prevent it
Related service
This problem usually connects to Aircon Service, Repair & Installation. Review service scope, pricing, warranty, and process before booking.
View Aircon Service, Repair & InstallationFAQs
Why is my aircon blowing warm air?
The most common causes are low refrigerant, a blocked coil or filter, or a failing compressor. A technician can diagnose it on site within 30–60 minutes.
Is topping up gas always the fix?
Not always. If there is a leak, topping up alone is temporary — the leak must be found and sealed first.
How much does fixing a not-cold aircon cost?
Basic servicing starts from RM 129, gas top-up from RM 2.50 per PSI, and compressor repair from RM 1,040. The final price depends on the actual cause.
Can I keep using a warm aircon?
It is better to stop and get it checked. Running a unit that is low on gas or has a blocked coil wastes electricity and can damage the compressor.