As temperatures rise, so do electric bills as air conditioners run more.  A three-step heating, ventilating and air conditioning test can help you determine if your AC unit is running at peak efficiency.

Before performing this test, the outdoor temperature should be above 80 degrees.  Set your thermostat below the room temperature to ensure the system runs long enough for the test.

1. Using a digital probe thermometer, measure the temperature of the air being pulled into the air conditioning filter. 
2. Measure the temperature of the air blowing out of a vent.
3. Subtract the vent output temperature from the filter intake temperature.  There should be a difference of about 17-20 degrees.  If the difference is less than 17 degrees, check the coolant level.  If the difference is greater than 20 degrees, check your ductwork restrictions.

Your HVAC system is essential to keeping your home comfortable.  If it breaks down, the equipment can be expensive to repair or replace.  With a little maintenance, you can add years to your system's operating life.