Electrical apparatus is designed to produce at full capacity at the voltage indicated on the rating plate. Motors operated at lower than rated voltage cannot provide full horsepower without shortening their service life. Low voltage can result in energy that is insufficient to energize relays and coils.
The Air Conditioning and Refrigeration Institute (ARI) certifies cooling units after testing them. The units are tested to make sure they will operate with 10 percent above or 10 percent below rated voltage. This does not mean that he units will operate continuously without damage to the motor. A large proportion of air conditioning compressor burnouts can be traced to low voltage. That is because a hermetic compressor motor is entirely enclosed within the refrigerant cycle, it is very important that it is not abused either by overloading or low voltage. Both of these conditions can occur during peak load conditions.
A national survey has shown that the most common cause of compressor low voltage is the use of undersized conductors between the utility lines and the condensing unit. Low voltage becomes extremely important when it is necessary to plug into an existing circuit. The existing load on the circuit may be sufficient to load the circuit. In this case, the air-conditioning unit will result in too much load, blowing the fuse or tripping the circuit breaker.
However, in some cases, the fuse does not blow and the circuit breaker does not trip. This reduces the line voltage, since the wire for the circuit is too small to handle the current needed to operate all devices plugged into it. Check the circuit load before adding the air conditioner to the line. This will prevent damage to the unit.