Dirty filters can cause heating and air conditioning systems to fail. It is more common then you think. Air conditioner coils ice up when there is not enough airflow across the coil. If this happens I advise you shut down the system and wait until the ice is completely melted away. This can take 24 to 48 hours. Heating systems tend to open limits when there is not enough airflow. After enough times the limits can stay open.
I personally have been on several calls where I have found iced up coils due to lack of airflow because of closed vents. one gets closed one day a month down the road another might get closed next thing you know your air conditioning or heating system is not getting enough airflow.
Most gas furnaces will try to tell you what is wrong by flashing a code. There is usually a window that the code can be seen through. You do not want to reset the power on the gas furnace before this code is obtained. The reason for this is if the issue is intermittent then the technician may not be able to reproduce it upon arrival. You will want to count the flashes and note how many fast flashes how many slow flashes the color of the lights this is all important information.
This sounds dumb but you would be surprised. gas furnaces generally always have a light switch within site of the unit. I have seen everything from someone putting a coat rack above it and when the coat was hung up the light switch was shut off. To someone not familiar with the house trying to turn on or off a garage light. Point is it does happen.
Some homes have 2 wires ran to the thermostat in these cases the batteries slowly drain down and the batteries need to be changed annually. Nothing more upsetting then paying a couple hundred dollars for 3 dollars in batteries. That being said if you replace then with batteries from your junk drawer ask yourself. Can you trust those batteries to be good?
If these steps do not provide a solution to your issue please give me a call. I will be happy to come repair or replace your heating or air conditioning system.