If you know the basic components of a central heat and air system you can repair many problems easily. Still not all problems can be fixed.
2. Verify if the system responds to different modification in the temperature. Raise the thermostat to maximum and wait to see if there are any changes. Do the same thing by turning it to the lowest level.
3. Verify the breaker switch inside the circuit breaker panel. Identify the one that controls the heating unit and see if it is on the “on” position. If it’s not then this was the problem and you should turn it on. Replace any burned fuse if necessary.
4. Further on, you can check the control unit, or most commonly, the furnace. Locate the On/Off switch and turn it once off and on and then wait a few minutes. See if the system starts to run again.
5. If you have a gas system, turn the shutoff valve counterclockwise and if you can’t then the gas is turned off. Locate the valve that controls the gas flow near the furnace. If the gas isn’t turned on rotate the valve clockwise to turn it on.
6. Identify the outdoor air conditioning unit and clean it for debris. The system can also malfunction because of trees and branches that can block the air flow.