Lint is a major culprit when it comes to long drying times. Be sure to clean the lint screen after each use and periodically check to see if there is residue on the screen, which can make your dryer less efficient. To check for residue, remove lint from the screen, then pour water over it. If the water does not go through the screen, it needs cleaning. Soap and water will do the trick.
Additionally, the lint can get into the air vents, blocking the way. You can disconnect the vents and use a vacuum or long tube to remove lint. Consider having a professional do a thorough cleaning.
Amount and Type of Clothing
Your dryer is most efficient when it's drying a full load of laundry. If you have too many items in the dryer, your clothes will take longer to dry. On the other hand, not placing enough clothes in the dryer can cause a similar problem.
Don't put too many of too few pieces of clothing in the dryer -- stick to the manufacturer's recommendations. Additionally, some types of clothing, like jeans or other heavy fabrics will require additional drying time.
Moisture Sensor Problem
Your dryer may have a moisture sensor that signals the dryer when the clothes are dry so it shuts off automatically. The moisture sensor can become dirty -- usually as a result of residue build-up from fabric softener sheets -- making it less efficient. Locate the sensor using your owner's manual and wipe it down with a wet cloth.
If you have an electric dryer, check the voltage of your outlet with the manufacturer's recommendation. Many dryers require a higher voltage outlet and will take longer to dry if you do not plug it into the correct type of socket. According to Frigidaire, if your dryer is on a 208-volt circuit, it will take 20 percent longer to dry your clothes than if the dryer is plugged into a 240-volt line.