AC not working can mean four different things, so decide which one you have first. Either it is completely dead, or it switches on but blows only air, or it cools weakly, or the fan runs and the outdoor part does nothing. Each one has a different likely cause, and the quick checks are not the same.
Many cases are fixed with a remote setting, a clean filter or a reset at the MCB. Anything that involves gas, the outdoor unit, the compressor, the boards or mains wiring is a job for a trained technician, and this page says clearly where to stop. If your AC is showing a code, find the brand on the AC error codes hub as well.
Common causes
1No power or a tripped MCB or stabiliser
How to tellNo lights on the indoor unit, the remote beeps but nothing happens
What fixes itCheck the MCB, plug point and stabiliser; reset once only
2Wrong remote mode or empty batteries
How to tellUnit is on but blowing room temperature air, or ignoring the remote
What fixes itChoose cool mode, set 24 degrees and replace the remote batteries
3Choked filter or iced coil
How to tellAir flow is weak, frost on the pipe or on the front, water dripping
What fixes itWash the filters; switch to fan only to melt the ice
4Low voltage or unstable supply
How to tellAC trips or restarts when other loads start, lights dim
What fixes itElectrician measures the supply; check the stabiliser capacity suits the AC
5Outdoor fan or compressor not running
How to tellIndoor fan works, air stays warm, outdoor unit is silent
What fixes itDo not open it; book a technician. See the compressor page
6Low refrigerant, leak or faulty sensor
How to tellCooling is slowly getting worse over weeks, or a code shows
What fixes itTechnician locates and repairs any leak before topping up the gas
How to fix it, step by step
Check that the power is really on
Look for the indicator light on the indoor unit. If it is dark, test the plug point with another appliance, check the MCB and look at the stabiliser. If the MCB trips again right after switching on, leave it off and call a technician.
Use fresh remote batteries and cool mode
Replace both remote batteries. Press the mode button until you see the snowflake or Cool, set 24 degrees and fan speed on auto. Dry, fan and eco modes can feel like the AC is not cooling.
Close doors and windows, check the room
A big room, open balcony door or direct afternoon sun can make a healthy AC look weak. Close the room, draw the curtains and give it 15 minutes.
Wash the indoor filters
Switch the AC off first. Open the front panel, lift the two mesh filters out, wash them under a running tap and let them drip dry in the shade before sliding them back. A clogged filter is the most frequent reason cooling feels weak.
Melt any ice
If you see frost, switch to fan only for 30 to 45 minutes. Do not scrape the ice. Ice often means a dirty filter, a low airflow or a low gas problem.
See whether the outdoor part wakes up
Check the outdoor switch is on and nothing covers the grille. Within a couple of minutes you should hear the fan and a low hum. Keep the casing shut and keep your hands away from it.
Reset the supply completely
After pressing off, let the AC's breaker stay down for a full ten minutes, then raise it. Small control glitches are wiped this way. Should a code show afterwards, find your brand on the hub.
Call authorised service
If the outdoor unit is silent, the air is warm, ice returns, or the MCB trips, stop using the AC. Share what you tried so the visit is quicker.
AC cooling not working while the blower keeps running
This is the complaint I hear most. The indoor blower is a plain motor and keeps spinning by itself, yet real cooling needs the outdoor part too. Warm air with a spinning blower often means the compressor will not start, the outdoor fan has stalled, the supply is too weak, or the gas level is low.
You switch on, the blower runs, and ten minutes later the air is still warm. Walk outside and see whether the outdoor fan is turning. If it is dead still, a remote or filter fix will not help. Read AC compressor not working and book service.
AC fan, swing, display and light problems
| Complaint | Likely cause | What to try |
|---|---|---|
| Indoor fan not working | Capacitor, motor or board | Power reset; then technician |
| Swing not working | Louvre motor or stuck vane | Remote batteries and reset; then technician |
| Display or light not working | Display setting, board | Press the display button on the remote |
| AC light blinking but not working | Fault code in a blink count | Count blinks; check the brand code page |
| AC switch or button not working | Worn switch or board | Use the remote; technician |
Low voltage and stabiliser problems
An AC compressor needs steady voltage to start. If the supply sags in the evening, the AC may stay dead, trip or run on the fan alone. A stabiliser can help only if its rating suits the AC, and if the AC stabilizer not working is your suspect, meaning the stabiliser is on but the AC is not working, the stabiliser itself may be the fault, so try the AC on a good direct supply for a short test if an electrician allows it.
Wiring and stabiliser repair should be done by a qualified electrician. Do not bypass a stabiliser, a fuse or the MCB.
When the AC is on but not cooling properly
Cooling that fades over weeks suggests dirty coils or low gas. Cooling that is fine at night but poor in the afternoon suggests a clogged outdoor coil or a unit too small for the room. A technician measures pressure and checks the coil, fan and sensors. The final bill grows with the age of the AC, how awkward the outdoor unit is to reach, and whether a compressor or board must be replaced.
Window AC versus split AC not working
A window AC fan not working while the AC is on points to a capacitor or fan motor, and a window AC is one box, so a fan with no cooling often means a failed capacitor or compressor in that box. A split AC has two units, so the outdoor part, the pipe and the link between them add more places to fail. Both types need clean filters and a clear airflow. If a fridge cooling not working problem is what you have at home, see fridge not working.
Frequently asked questions
Why is my AC not working but the power is on?
The remote may be in fan or dry mode, the batteries may be weak, or the outdoor part may not be starting. Check the mode and batteries first, then listen for the outdoor unit.
Why is my AC working but not cooling?
Common reasons are a dirty filter, an iced coil, a stopped outdoor fan, a compressor that is not starting or low gas. Do the filter and ice checks, then call a technician.
Why is the AC fan working but cooling is not?
The indoor blower runs on its own circuit, separate from cooling. A silent outdoor fan or compressor leaves the air warm. Leave the outdoor casing closed and book service.
Why is my AC not working after a stabiliser is on?
The stabiliser may be the faulty part, the voltage may be too low for it, or its rating may be too small. An electrician can test it.
What does a blinking light on an AC mean?
Many ACs use a blink count to show a fault code. Count the blinks and match them to your manual or brand code page.