If you don't change the AC filter, it will start to fail. You will no longer be able to filter the air properly, allowing dust and contaminants to enter the air conditioner. Dust clogs moving parts of an air conditioner, such as motors and fan valves. Airflow is restricted, creating a strain on the system.
A dirty filter reduces airflow to the HVAC system and makes it work harder, using more energy and costing you more money. If the air filter is clogged and can't trap contaminants like it did before, those things can go back to the air that everyone in your home breathes. This can lead to immediate problems such as headaches, itchy eyes or throat, and dizziness. If air filters are not changed and problems persist, long-term effects could be respiratory disease, heart disease, or cancer.
The danger of not changing the air filter in the house for a long time is that it will eventually lead to damage to the oven. This means that the entire system will be destroyed by excess heat. Probably the biggest danger of not changing the filter in your air conditioning oven is that it can damage your HVAC system and reduce its life expectancy. As a licensed home inspector, if you don't regularly change the filter, you can reduce the life expectancy of your air conditioner from 6 to 12 years.
If the air cleaner is not serviced often enough, it will eventually become clogged to the point where air cannot pass through it. When the oven is running, the lack of air flow will trap heat in the system. As the temperature inside the system continues to rise, the limit switch will turn the oven on and off to prevent it from overheating. This will temporarily mitigate the problem, but will not resolve the root of the problem.
Without a new air filter, the oven will overheat every time it is turned on again. This is known as short cycling. A clogged air filter can also cause the air blower to break down, which in turn causes the entire HVAC system to break down. And when the filter is clogged, that dust clumps into the evaporator coil (or coil A) of your HVAC system, which will greatly reduce its efficiency.
In addition to damaging your air conditioning system, neglecting AC filter changes can also cause mold to form on vent covers, ducts, and inside the air conditioning controller. The more people who live under your roof, the more often you'll need to change your air filter, so be sure to check it often. You should only change the filter every 6 months if you have a 5 inch thick high efficiency filter, not the standard 1 inch filter. As air moves through a building's HVAC system, air filters trap and pick up large and small particles such as dust, allergens and microorganisms.
If you find that old filters look like nothing, not even air could pass through them, it's time to contact an HVAC professional. And if you're really bad at not changing the filter (that is, you actually work on it), you may experience the result of a system failure such as a broken compressor, leaking refrigerant lines or a faulty fan. In addition to damage to your air conditioning system, not changing the filter frequently also results in a poor life experience.