how to check if room ac is working properly
1 Check outside to see if there is anything blocking the condenser and make sure to trim any foliage back at least 2 feet. 2  Dirty air filter. 3  A dirty air filter can reduce your air conditioner's air flow and damage your unit, preventing it from properly cooling your home. Dirty air filter. 2  A dirty air filter can reduce your air conditioner's air flow and damage your unit, preventing it from properly cooling your home. 3  Make sure to check and change your filter once a month. 4  Incorrectly sized unit.