A dirty air filter will provide some protection against dust particles that can damage your air conditioning system, but it's still better to have a filter than to have none. Although it is possible to run an air conditioner without a filter, it is never recommended. If you don't have a new replacement filter on hand, it's best to wait until you can get one before running the system. Running an air conditioner without a filter is worse than running it with a dirty one.
Doing so puts your system at risk of serious and costly problems. To keep your air conditioner running efficiently for longer, clean or replace the filter regularly, depending on the type of filter. An air conditioning system has a filter to prevent dirt and debris from entering the unit and entering the indoor environment. The MERV rating indicates the percentage of particulate matter that the filter will remove from the air passing through it.
A dirty filter forces the HVAC unit to work harder than normal because it finds it more difficult to draw air. A unit that works too much consumes more energy and is more likely to break down prematurely. If you install a new filter, but don't turn on the heating or air conditioning until a month or two later, the filter should still be relatively clean, since the system hasn't been forcing air through. But if your electricity bill is higher than usual (other summers), a clogged air filter could be the cause.
A good air filter helps prevent dust and dirt from accumulating on all internal components of the unit; a bad one will cause additional wear and tear that can lead to serious maintenance problems in the future. When you operate your air conditioner without an air filter in place, the air conditioner sucks in “dirty air” and circulates that air back to your home. It's important to remember that having no filter is worse than having a dirty one. To keep your system running efficiently for longer, make sure to clean or replace your filter regularly.
If you don't have a new replacement filter on hand, wait until you can get one before running the system.