1) First thing is first – If your system doesn’t come on, check your circuit breakers and disconnect switch. The Disconnect is located outside, usually mounted on the house next to the Air Conditioner unit.
2) Another common cause is blocked air filters, so check that they are clean. An air filter should be cleaned or replaced on average every 3 months.
3) Check all return air grilles to make sure they are NOT blocked by furniture.
4) Changing your thermostat quickly, from one temperature position to the next may cause the compressor motor circuitry to go into safety mode temporarily. When this happens the compressor will turn off for a short period of time. Although the fan may still be running. Allow 15 minutes for compressor to automatically reset itself.
5) Check your blower compartment door on the furnace itself making sure it is shut tightly. The equipment will not run if the door is not secured.
6) Check outdoor condenser for any blockages, such as leaves, plastic or other debris. Enclosures around your outside unit can interfere with proper operation as well. The unit needs lots of breathing room.
7) Sometimes you may experience rooms cooler or warmer than others. You can balance airflow to the way that makes you feel the most comfortable. Just pull the lever on the registers so that the louvers point downward to decrease and upward to increase airflow. Keep in mind that when increasing airflow for one area you reduce it in other areas of the house. It is normal to make needed air flow adjustments on a seasonal basis. What works well for summer, may not work well for the heating season.