Universal air filter in polyurethane for air conditioners. any air conditioner has the air filter that collects and blocks impurities that are dispersed in the environment including viruses and bacteria. many of these viruses end up being hibernated by the low internal temperature of the air conditioner but when the conditioner is turned off and stops producing cold they only wake up when it starts to run out of circulation. the air conditioner therefore is dangerous when re-igniting if the filters are not cleaned and replaced with regularity and care.