AC Not Cooling But Running? 15 Real Reasons Your AC is Blowing Warm Air in Dhaka
It’s 38 degrees outside in Dhaka. You come home, turn on the AC, and wait. Twenty minutes pass. The fan is running, the compressor hums, but the air coming out of the vents feels barely cooler than the room itself. I’ve seen this exact situation hundreds of times across Dhanmondi, Gulshan, Mirpur, and Uttara — and it almost always comes down to one of these 15 issues.
As someone who runs Mohammadi Engineering Ltd., a team that has handled thousands of AC repair calls in Dhaka since 2020, I’ll walk you through every possible cause — from the ones you can fix yourself in two minutes to the ones that need a trained technician with proper equipment.
What’s Covered in This Guide
- Quick 5-point diagnosis you can do right now
- 15 reasons your AC is running but not cooling
- DIY fixes vs. when to call a professional
- Cost estimates for common repairs in Dhaka
- Frequently asked questions
Quick Diagnosis: Check These 5 Things First
Before you call anyone, spend two minutes on this checklist. It saves you from paying a visit charge for something trivial.
- Is the thermostat set to “cool” mode, not “fan” or “heat”?
- Is the temperature setting lower than the current room temperature?
- Is the air filter visibly clogged with dust?
- Is the outdoor unit (compressor) actually running, or just the indoor fan?
- Are all the air vents in the room fully open and unblocked?
If all five check out and the AC still isn’t cooling properly, you’re dealing with one of the issues below.
15 Reasons Your AC is Running But Not Cooling
Clogged Air Filter
This is the number one cause we see in Dhaka homes. Dhaka’s dust levels are notoriously high, and filters get choked within 4-6 weeks during dry season. A blocked filter cuts airflow by up to 50%, which means the evaporator coil can’t absorb heat properly. The AC “runs” but can’t cool. Slide the filter out, hold it against light — if you can barely see through it, wash it or replace it.
Low Refrigerant (Gas Leak)
If your AC was cooling fine last month and suddenly stopped, low gas is the most likely culprit. Refrigerant doesn’t “get used up” — if it’s low, there’s a leak somewhere. Running an AC with low gas damages the compressor over time. This needs a proper AC gas refill service in Dhaka with leak detection, not just topping up the gas.
Dirty Evaporator Coil
The evaporator coil sits behind the air filter and is responsible for absorbing heat from your room air. When dust gets past the filter (or when the filter is missing), it coats the coil in a layer of grime that acts as insulation. Cold air can’t pass through. This requires professional chemical cleaning — part of a thorough AC servicing in Dhaka.
Blocked or Dirty Condenser Coil (Outdoor Unit)
Your outdoor unit dumps the heat your AC removes from the room. If the condenser coil is covered in dirt, cotton from trees (common near Dhanmondi and Gulshan parks), or debris, it can’t release heat. The system overheats and cooling drops dramatically. Keep at least 2 feet of clear space around the outdoor unit.
Compressor Issues
The compressor is the heart of your AC. If you hear the outdoor unit running but the compressor isn’t kicking in (no change in sound when it should start), it could be a bad capacitor, burnt winding, or locked rotor. Compressor problems are serious — ignoring them often leads to full replacement costing ৳15,000-25,000. If you suspect this, get emergency AC repair right away.
Faulty Capacitor
The capacitor gives the compressor and fan motors the electrical jolt they need to start. A weak or dead capacitor means the fan might spin slowly or the compressor won’t start at all. You might notice a humming sound from the outdoor unit. Capacitor replacement is cheap (৳800-1,500) but needs to match the exact microfarad rating.
Thermostat Malfunction
Sometimes the thermostat sends wrong signals — it might think the room is already at the set temperature and keep the compressor off while the fan keeps running. Test this by setting the temperature 5 degrees below room temp. If the compressor still doesn’t start, the thermostat or its sensor might be faulty.
Incorrect AC Size for the Room
A 1-ton AC in a 200 sq ft room with large windows facing west, three people, and computers running will never cool properly. In Dhaka’s climate, you roughly need 1 ton per 120-140 sq ft for a standard room, but factors like sun exposure, floor level, and insulation change this significantly. If you’re dealing with this, check our AC installation guide for Dhaka.
Leaking or Disconnected Ductwork
Relevant if you have a central HVAC system. Duct leaks can lose 20-30% of cooled air into your ceiling or walls before it reaches the room. This is harder to diagnose — you’ll need a professional to check duct pressure and connections.
Refrigerant Line Blockage
The copper pipes connecting your indoor and outdoor units can get restricted due to poor installation (kinked pipes), moisture in the system forming ice, or debris. This causes uneven cooling or complete loss of cooling on one side of a multi-split system.
Fan Motor Problems
If the indoor fan runs but the outdoor fan doesn’t (or runs very slowly), the condenser can’t reject heat and the system shuts down on high-pressure protection. Similarly, if the indoor fan is weak, you won’t feel adequate airflow even if cooling is happening. Worn bearings, weak capacitors, or burnt motors are the usual causes.
Ice Buildup on Evaporator Coil
If you notice ice forming on the indoor unit or the copper pipes, something is wrong. Low gas, poor airflow (dirty filter), or a faulty expansion valve can cause the coil temperature to drop below freezing. Running an iced-up AC damages the compressor. Turn it off, let the ice melt, and call for inverter AC repair if it keeps happening.
Electrical Issues or Loose Wiring
Dhaka’s voltage fluctuations damage AC components over time. Loose connections at the terminal board can cause intermittent operation. If your AC sometimes cools and sometimes doesn’t, or trips the MCB, get the electrical connections checked before it burns a more expensive component.
Reverse Valve Problem (Heat Pump Systems)
Some split AC systems have a reversing valve for heating mode. If this valve gets stuck in the heating position, your AC will blow warm air in cooling mode. This is more common in newer inverter models that auto-switch modes.
PCB Board Failure
The printed circuit board controls every function. Power surges (very common during load shedding in Dhaka when electricity returns), moisture, or component aging can damage the PCB. Symptoms include random shutdowns, error codes on the display, or the AC not responding to the remote. PCB repair or replacement needs an experienced technician.
DIY vs. Professional: What You Can Fix Yourself
| Problem | Can You Fix It? | Why |
|---|---|---|
| Clogged air filter | Yes | Wash with water, dry, reinstall |
| Wrong thermostat setting | Yes | Check mode and temperature |
| Blocked outdoor unit | Yes | Clear debris, wash gently with hose |
| Tripped MCB | Yes | Reset the breaker once |
| Low refrigerant | No | Needs gauge set, leak detection, licensed gas |
| Compressor issue | No | Requires electrical testing equipment |
| Capacitor replacement | No | Wrong rating can damage compressor |
| PCB failure | No | Needs soldering and component-level repair |
| Dirty evaporator coil | No | Needs chemical cleaning and proper rinse |
Estimated Repair Costs in Dhaka (2025)
| Repair Type | Estimated Cost (৳) | Time Needed |
|---|---|---|
| Air filter replacement | 300 – 800 | 5 minutes |
| AC gas refill (R32) | 2,000 – 3,500 | 45 – 60 min |
| Capacitor replacement | 800 – 1,800 | 20 – 30 min |
| Full AC servicing | 1,500 – 3,000 | 60 – 90 min |
| PCB repair | 2,500 – 6,000 | 1 – 3 hours |
| Compressor repair | 5,000 – 12,000 | 2 – 4 hours |
| Compressor replacement | 15,000 – 25,000 | 3 – 5 hours |
These are approximate ranges based on what we charge at Mohammadi Engineering Ltd. across Dhaka. Prices vary by AC brand, tonnage, and parts availability. We always provide a written estimate before starting any work — no surprises.
Why You Shouldn’t Ignore a “Running But Not Cooling” AC
Continuing to run an AC that isn’t cooling properly leads to a chain of expensive problems:
- Compressor overheats and burns out — the most expensive component to replace
- Electricity bill stays high even though you’re getting zero cooling benefit
- Refrigerant leak worsens, potentially releasing harmful gases
- Ice formation can crack the evaporator coil
- Moisture buildup leads to mold growth inside the indoor unit
If you’re in Dhaka and your AC isn’t cooling, contact our team at Mohammadi Engineering Ltd. We operate 24/7 across all major areas including Dhanmondi, Gulshan, Mirpur, Uttara, Mohammadpur, and Khilgaon. Our technicians arrive with all common spare parts, so most repairs are completed in a single visit.
AC Not Cooling? Get It Fixed Today
Our technicians are available 24/7 across Dhaka. Call now for same-day repair with a 30-day service warranty.
Call: 01859-976686Frequently Asked Questions
The most common reasons are a clogged air filter, low refrigerant gas, dirty evaporator coil, or a faulty compressor. In Dhaka’s dusty conditions, filter clogging accounts for nearly 40% of these cases. Start by checking and cleaning your filter, then check if the outdoor unit compressor is actually running.
Key signs include: the AC takes much longer to cool than before, ice forming on the copper pipes near the indoor unit, hissing sound from the indoor unit, weak airflow from vents even when the fan sounds normal, and higher electricity bills without increased usage. A technician can confirm with a pressure gauge reading.
You can fix a dirty filter, wrong thermostat setting, and blocked outdoor unit yourself. Everything else — gas refill, coil cleaning, compressor work, capacitor replacement, and PCB repair — needs a trained technician with proper tools. Attempting these without training risks permanent damage to your AC.
Simple repairs like filter cleaning or capacitor replacement take 15-30 minutes. Gas refill takes 45-60 minutes. Full servicing takes 60-90 minutes. Compressor replacement takes 3-5 hours. We at Mohammadi Engineering Ltd. stock common parts, so most repairs are completed in a single visit without waiting for parts.
First check if the outdoor unit is running. If not, check if the MCB has tripped. If the outdoor unit runs but there’s no cooling, turn off the AC and check for ice on the pipes. If you find ice, let it melt completely before turning it back on. For emergency situations at night, call a 24/7 service like Mohammadi Engineering Ltd. at 01859-976686.
Yes, significantly. Refrigerant carries the lubricating oil that keeps the compressor running smoothly. Low gas means less oil circulation, causing the compressor to overheat. Running an AC with low gas for extended periods is the number one cause of premature compressor failure, which costs ৳15,000-25,000 to replace.