A gas heater is a device that uses liquefied gas for heating. Since it is connected to a gas source, cleaning it is quite easy. Keeping the gas heater in good condition by cleaning it from time to time is important to prolong its durability. Cleaning the gas heater regularly is also important from a safety perspective, because deposits in the flue, or anywhere else in the device, can sometimes lead to problems.
If the gas furnace is not running, the power could be disconnected, the motor overloaded, or the gas supply insufficient. Check each of these components individually, ensuring the gas heater has sufficient power and that the motor is running (you will be able to hear if it is running when it kicks on). Check the gas reserves tank to ensure there is gas in it. If these systems function properly and you are still having difficulty, your heater may need to be cleaned or repaired.
If your heater is not heating properly, dirt in the gas lines--and especially the burner ports--could be the cause of the problem. First, disconnect the lever that connects the gas supply to the appliance. The burner ports are the parts that distribute the gas supply into the heater. They have to be cleaned with the help of a toothbrush or flask cleaner. The part called the burner access panel, which is located at the tank's lower part, may also have to be replaced if there is a dirt buildup. This piece can be purchased at your local home improvement store and replaced according to the directions on the package. Generally, this should be replaced every two years.
If your heater is turning on and off repeatedly this could be caused by dirt in the filter or lack of lubrication in the motor or blower. Check your users manual to locate the filter (it is usually a large piece that slides in and out of your gas heater from the side), remove it after the gas has been turned off, and wipe off any excess dirt. Alternatively, you can replace the filter entirely rather inexpensively. Simply remove the filter, write down the model number and get a replacement from your local home improvement store.