• Check if the thermostat has been set in cooling mode. Also check if it is working and batteries have not run out.
• Also check if the indoor unit is running properly. Do this by feeling the air that is being blown out of the vents.
• Now go to the outdoor unit. Keep your ears close to it; try to feel the sound of the compressor. You will encounter one of these situations –
• Compressor is running
• Or the compressor is not running
If the compressor is running
The fault lies in the fan motor or there is a bad capacitor. As the compressor is running, 220 volts of power is being supplied to it by the contractor. The contractor also supplies power to the motor. So the contractor and compressor are fine. You have to check two things now the capacitor and the fan motor. The former can be checked with a multi-meter that has the ability to read micro farads. If you are not quite comfortable about testing electrical devices take out the parts (capacitor and the fan motor) and take them to nearby HVAC Repair Company.
Testing the capacitor
If you want to test the capacitor yourself, do so by turning off the air conditioner. Remember, capacitors can store an electric charge (like a battery). Discharge the capacitor by shorting between capacitor terminals with a screwdriver. Now remove the wires from the terminals. Set the multi meter meter to read above 10k and 1m ohms. Connect the leads of the multi meter to the corresponding leads on the capacitor, red to positive and black to negative. The meter should start at zero and then moving slowly toward infinity. If it is doing so it is fine. Otherwise it is faulty and needs to be replaced.