It has been a long time since gas dryers came with pilot lights that you have to light manually. In fact, the last such dryer was manufactured in 1994. Since that time, gas dryers have come with electronic ignition mechanisms that light the burner whenever the controls call for heat. A dryer manufactured before 1994 could almost be considered an antique, but you may find yourself using one after moving into an apartment or an older house. Needless to say, the dryer won't get warm if the pilot isn't burning, so here's how to relight it if it goes out.
Locate the Pilot and the Gas Valve
The easiest way to find the gas valve is to follow the gas line from the main shut-off to the base of the dryer. The gas valve will be located on the same side of the dryer as the gas line. In most cases, you can access it by removing a panel from the front of the dryer. The panel may or may not have screws that you have to remove to get it off. After removing the panel, look on the inside. You might see directions for lighting the pilot, but you probably won't need them. The directions aren't likely to vary much from the following procedure.
Procedure For Lighting the Pilot
Locate the gas control, which is usually a large, red knob on the front of the gas valve. You'll see a marker on the knob and three positions for it on the adjoining plate. Turn the knob to the "off" position and wait five minutes before doing anything else. This gives residual gas in the burner and pilot tube time to clear out.
After the waiting period is over, turn the knob to the "pilot" position and hold it in while you hold a lighted match or lighter to the pilot orifice. Remove the heat when the pilot lights, but keep the knob depressed for about 20 seconds to give the thermocouple time to heat up. Release the knob and ensure the pilot stays lit, then turn the knob to the "on" position and replace the panel on the front of the dryer. The dryer is now ready to use.
Pilot Won't Light or Won't Stay Lit
If you can't get the pilot to light at all, check the main gas shutoff to make sure it's on. If you still can't get the pilot to light, the most likely reason is a blockage in the pilot tube. You'll have to disassemble the pilot tube to clean it with compressed air, so if that procedure is beyond your skill level, it's time to call a pro.
The pilot may light but go out as soon as you release the control knob, no matter how long you hold the knob in before releasing it. That usually indicates a problem with the thermocouple. Sometimes, repositioning the thermocouple takes care of this issue, but often the only remedy is to replace the thermocouple. Again, it's time to call in a pro if this type of repair isn't up your alley.