My guess is that you either have a bad blower regulator (replaced mine last week) or your pushbutton is on the fritz.

Since the 140's are known for their weak regulator it is probably a safe place to start. I found one on Ebay brand new for $149 shipped. Very easy to replace. Less than 15 minutes and a phillips head screwdriver. Email me and I will be happy to hook you up with the guy that sells them. I believe that they are $375 list but these are NIB for $149.

Brian