To determine how dirty the filters are, hold them up. If you can easily see light through them, then they're still clean enough to use. Get a yearly planned maintenance check on equipment. At a minimum all safeties, controls and filters will be checked. Inspect the blower for worn, shiny or sagging belts.
Worn belts can cause undue stress on the fan motor.
Never run your air conditioner when outside temperature is below 600F. Coils may frost up, restricting air flow. Wait at least 5 minutes before restarting your air conditioning unit. This relieves stress on the compressor. Keep drapes, curtains and furniture away from registers and returns. This will help air flow and make your home more comfortable.