One of several things is going on:
First, check the circuit or fuse box. One circuit or fuse can be blown; it'll still turn around, but not heat. This might only happen when there is the pull-out 2 buss fuse arrangement
Next, you might have a bad heating element.
Could be the switch too (but doubtful)
And absolutely, check to make sure the vent is not clogged with gross, wet lint, and is completely free flowing with air.
david, December 2007