A few basic principles for Air Conditioner troubleshooting. For both central home air conditioner or window air conditioners, the very first thing to test is whether the unit is getting proper power. If the unit uses 220 volt power be sure that the correct voltage is dealing with the unit. Same for 110 volt units. A voltage meter can be used to assure that the voltage is correct.
For window air conditioning units the voltage can also be checked before and after the thermostat. If voltage has been supplied to the thermostat although not from it then the thermostat probably needs replaced. This can be a fairly common problem. Another place to test may be the fan motor voltage. The fan on window air conditioners runs the indoor blower and the condenser fan.
If that motor fails compared to compressor may run for a short time, but will overheat and shut off. Continued operation like this will result in compressor failure. This motor can be economically replaced for larger window air conditioners, but for smaller ones the price of replacement may well be more than the usual new unit.
Central Air Conditioners for your home are more complicated and there are many issues that can go wrong. Much like the window air conditioner the thermostat can also be a problem. The central air conditioner thermostat will only have 24 volts going to it. So don't look for high voltage there.
Some units the voltage will soon be coming from the outdoor unit and dc to ac converter price in bangladesh others the voltage will soon be supplied by the indoor air handler or furnace. Most home central air conditioning will soon be supplied by the indoor air handler or the furnace. If the air conditioner is for cooling only the unit will usually have only two wires going to the condenser unit. Make sure that you've 24 volts across those wires.