Where possible, air conditioning units should be backed up by a generator rather than an uninterruptible power supply.
Air conditioning systems are considered something of a “dirty load” because of the continual switching, which causes spikes and surges to both the voltage and current. While UPSs can handle certain levels of overload for a small duration, the current surges typically found with air conditioning units tends to be greater than the UPS’s capacity.
If there’s no option other to use a UPS to support A/C, it is recommended to oversize the inverter by as much as four to five times to ensure the UPS will be able to support the load and eliminate the risk of failure.
Another option that reduces the risk is to operate a separate, dedicated UPS system just for the air conditioning system, with another UPS backing up the critical load.
However, this obviously does significantly increase costs and require a bigger footprint.