This issue could be why your dryer takes multiple loads to dry clothes, and here's how to fix 

I recently did a deep cleaning on one of our dryers and discovered a massive lint ball like that. It now works like new. 😄

Thank you for this video and information. You saved me a lot of time and money. I found the problem right away. The outside vent door was stuck shut. I opened it up, cleaned out the lint, and the dryer is now running perfect. Many blessings to you!

Thank you

Wow!!! Let me check mine

I have a basic GE dryer that is just time based cycles. It does not have a sensor to detect when clothes are dry. It is like an old school timer based dry cycles. Recently its been leaving me with damp clothes. The dryer is heating but I'm not sure if it's heating up enough. I did clean the hose, vent, and got a pretty good bit of lint out of the vent, hose, and where the hose connects to the dryer. I went to the vent and it appeared to be getting really good air flow and the air was hot - however my clothes were still lightly damp when cycle was complete. I always dry using medium heat instead of high heat. The dryer is getting somewhat hot/warm but I cant say if its as hot as it supposed to be. So as of now all i can say is A) its heating up B) appears to have good air exhaust flow C) clothes are still damp. Do you think this is going to be most likely a thermostat issue or heating element issue? I guess it would be pointless to test for continuity in the heating element b/c it is producing heat but Im not really sure if its getting hot enough. I'm not even sure if my dryer has one of those safety cut off thermostats like on this video.

How do you stop the air duct from accumulating dust like that?

I have checked the continuity of the thermostat and heat sensor and cleaned the lint from the dryer. It still takes at the very least 2 cycles to dry. Any ideas?