Okay, I have a dryer and the duct work is under the basement. I noticed that the duct work was disconnected ,when I connected the duct work properly my auto timer dry period stopped working, now I disconnected the duct work under my house to about 5 ft and let the hot air blow under my crawl space, now the dryer works fine... any ideas.

Sounds like the duct is clogged with lint between the point where it was disconnected and where it outlets, outside. Having it disconnected as it presently is, is not a good idea as it will produce too much moisture into the crawl space.
Some newer model dryers have a sensor that can determine that the exhaust is not working properly, as yours is likely doing.
You can purchase a brush to push through the duct to remove blockages. Similar to: Search Results for dryer duct brush at The Home Depot

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Originally Posted by smearcase

Sounds like the duct is clogged with lint between the point where it was disconnected and where it outlets, outside. Having it disconnected as it presently is, is not a good idea as it will produce too much moisture into the crawl space.
Some newer model dryers have a sensor that can determine that the exhaust is not working properly, as yours is likely doing.
You can purchase a brush to push through the duct to remove blockages. Similar to: Search Results for dryer duct brush at The Home Depot

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Well I do smell the dryer heat coming from the outside of my house, but maybe I should just replace the whole duct vent...

I was able to get into a position where I could inspect mine with a good bright light.
I would verify that it is clogged and try to unclog it first (before replacing) - unless it is an inferior duct which snags lint and poses a fire hazard.
This appears to be a good video on the subject:
How to build a safe dryer vent. Best marerials to use for a dryer vent. - YouTube
Good luck.

Thanks for all your help. I decided to just replace the duct work and move it to a different location since the vent blows out under my deck outside. 2 questions, would it effect the deck if I keep it there and how far is too long for the duct work?