Why Your AC Is Not Cooling — 8 Real Causes and Fixes (Lahore Guide)
If your air conditioner is switched on, the fan is running, but the room is still hot — you are dealing with one of the most frustrating AC problems we see every summer in Lahore. The good news is that in most cases, the cause is fixable. The bad news is that there are several possible causes, and diagnosing the wrong one wastes time and money.
We have been repairing ACs across Lahore since 2015. These are the 8 most common reasons an AC runs but does not cool — and what to do about each one.
1. Low refrigerant gas
This is the number one cause of poor cooling in Lahore. Refrigerant is the substance that absorbs heat from your room and carries it outside. When gas levels drop due to a leak, the AC cannot transfer heat properly and the room stays warm.
Signs: The AC runs continuously, the room barely cools down, or you see ice forming on the indoor unit or copper pipes
Fix: A technician needs to find the leak, repair it, and refill the gas. Simply topping up gas without fixing the leak means the problem returns in weeks. At Xpert AC Service, gas refilling with leak repair starts from Rs. 2,800.
2. Dirty evaporator coil
The evaporator coil inside your indoor unit absorbs heat from the air. When it gets coated in dust and grime — which happens fast in Lahore’s dusty climate — it cannot absorb heat efficiently. The result is warm air blowing from your AC even though the unit is working.
Signs: Reduced cooling over time, the AC feels less effective than it used to.
Fix: A professional coil cleaning, which is part of our deep cleaning service starting from Rs. 2,500.
3. Dirty or blocked air filter
A clogged air filter restricts the airflow going into your AC unit. Less airflow means less cooling. This is the most common and easiest-to-fix cause of poor AC performance in Lahore homes.
Signs: Weaker airflow from the indoor unit, dusty smell when AC is running.
Fix: Remove the filter, wash it under running water, dry it fully, and put it back. This takes 10 minutes and costs nothing. Do this every 3 to 4 weeks during summer.
4. Undersized AC for the room
Many homes in Lahore have ACs that are too small for the room they are cooling. A 1-ton AC in a 250 square foot room on a south-facing wall in July will never get the room properly cold — no matter how well it is serviced.
Signs: The AC runs all day but the room never reaches the set temperature.
Fix: Check whether your AC capacity matches your room size. A rough guide for Lahore: 1 ton for up to 120 sq ft, 1.5 ton for 120–180 sq ft, 2 ton for 180–250 sq ft. If your room is larger or has poor insulation, go up one size.
5. Outdoor unit blocked or dirty
The outdoor unit (condenser) releases the heat absorbed from your room into the outside air. If it is blocked by a wall, covered in dust, or surrounded by debris, it cannot release heat efficiently — so your room stays warm.
Signs: The outdoor unit feels extremely hot to the touch, or the AC trips off due to overheating.
Fix: Make sure the outdoor unit has at least 30 cm of clear space around it. Spray it down with a garden hose (unit off at the breaker) to remove dust from the fins. For a thorough cleaning, book a deep service.
6. Faulty thermostat or remote setting
Sometimes the issue is not mechanical at all. If the thermostat is set too high, or the remote is set to “fan only” mode instead of “cool” mode, the AC will run without cooling.
Fix: Check that the mode is set to cooling (snowflake symbol), not fan-only or dry mode. Set the temperature to 24–26°C for efficient cooling. If the remote is faulty, a replacement costs Rs. 500 to Rs. 1,200 depending on the brand.
7. PCB or capacitor failure
The PCB (printed circuit board) controls all functions of the AC. The capacitor starts the compressor and fan motors. When either of these fails — which is common in Lahore due to voltage fluctuations — the AC may run but the compressor does not start, meaning no cooling occurs.
Signs: The indoor unit blows room-temperature air, the outdoor unit is silent even when the AC is running. Fix: This requires a technician with proper diagnostic equipment. Capacitor replacement typically costs Rs. 800 to Rs. 2,000. PCB replacement is more expensive at Rs. 2,500 to Rs. 6,000 depending on the AC brand and model.
8. Compressor failure
The compressor is the heart of your AC. If it fails, the AC cannot cool at all. Compressor failure is usually caused by prolonged running with low gas (the compressor overheats), voltage damage, or just age.
Signs: The outdoor unit makes a clicking or humming sound but does not run. Or it runs for a few seconds and then cuts off.
Fix: Compressor replacement or repair. This is the most expensive AC repair, typically costing Rs. 4,500 to Rs. 12,000 depending on the brand and tonnage. For older ACs, it may be more cost-effective to replace the unit entirely.
How to diagnose the problem yourself
Before calling a technician, do these three checks:
- First, clean your filter and make sure the outdoor unit has clear airflow around it.
- Second, check that the remote is set to cooling mode at 24°C. Third, look at your indoor unit — if you see ice on the coil or pipes, that points to low gas.
- If these checks do not solve it, call us at 0340-1424525. We will diagnose the problem on-site and give you a price before starting any work. We serve all areas of Lahore with a typical arrival time of 1 to 2 hours
nice info