One of the most important things you can do for your air conditioning system is change the air filter regularly. The challenge comes when you check the filter every 30 days and it's not getting dirty.
You may have heard before how important it is to change the air filter on your cooling and heating system each month. A clogged or dirty filter can block air flow and make your system operate less efficiently. Occasionally I hear another concern from customers, "What's going on if my air filter is not dirty?"
According to ENERGY STAR, 20 to 30 percent of the air that moves through your duct system is lost because of leaks, holes, and poorly connected ducts[1]. Your air filter may not be dirty because all the air is not going through it. The duct system in your home may be leaking and providing a way for the air to bypass the filter and get into your system without being filtered. When your duct system is leaking it is blowing air into your crawl space or attic, depending on where the duct system is located, and taking the air from the same location and putting it back into your system. The Department of Energy says air that bypasses the filter may carry dirt directly into the evaporator coil and reduce the coil's ability to work[2], thus reducing the efficiency of your system. One of the main culprits of breakdowns of HVAC systems is dirt.
A qualified, trusted professional can check your duct system for leaks and make sure your cooling and heating system is operating at peak performance. This can help with energy efficiency and ultimately savings on your utility bill.
Your friend in comfort and energy savings,
Derek Cole
[1] http://www.energystar.gov/index.cfm?c=home_improvement.hm_improvement_ducts
[2] http://energy.gov/energysaver/articles/maintaining-your-air-conditioner