Most people automatically assume the dryer is the reason their clothes aren’t getting dry. Usually the first call most people make is to the appliance repairman. This is a mistake. The problem is almost always the dryer vent.
If your dryer is producing heat but takes over 55 minutes to dry a load that’s one sure sign your dryer vent needs cleaning. Over time your dryer vent accumulates lint and can become completely blocked if not cleaned regularly. Occasionally the blockage can damage the dryer’s thermostat as well. A bad thermostat can be hard to diagnose as the dryer will still be producing heat.
One way to test your dryer vent for blockage is to put your hand on the top of the dryer while it’s running. If the dryer is hot to the touch you most likely have a restricted dryer vent. The top of your dryer should never be hot, warm only. A dryer is designed for the heat to be going out. If it’s not going out your dryer is just going to get hot. Hotter than it ever would if it were venting properly
Sometimes a restricted dryer vent will cause lint accumulation on the inside of the dryer door. When your vent becomes obstructed the suction that would normally direct the lint to the screen becomes weak or nonexistent. This can leave lint on the inside of the door and on your clothing.
If you’re still not sure the vent is the problem, you can disconnect the dryer vent transition from the wall and dry a load of clothes. If your clothes get dry in 55 minutes or less the problem isn’t your dryer. It’s the vent. Keep the dust to a minimum by putting an old nylon over the transition. Just a reminder never vent a gas dryer vent into your house. Gas produces carbon monoxide that must be vented outside.