Once your Air Conditioning Unit is too hot, then it is a sign that you may need to replace your air filter because your unit is doing more work than usual, to reach its desired output. In the long run, it will damage your unit. Once the air is not cold enough, then you need to check your filters as well. Failure to frequently change your unit will increase your electricity bill since your unit is working double the usual. You get more allergy and respiratory attacks plus there is more dust on the air vents.