not really mechanical but annoying and age related. i have a 2002 e450 chassis with about 121,000 miles
last summer i lost my dash AC, it started blowing out of the defrost vents only. this is a default for Fords so if you lose HVAC you still get defrost capability.
there is a short rubber hose after the vacuum chamber powered by the exhaust manifold UNDER the ac system. 20 hour repair by the book, draw down ac, pull battery, battery tray and ac system. this hose dry rots and eventually breaks. i rerouted the PVC vacuum line and put in a different vacuum chamber under the passenger side dash. tied that into the existing system after the failed vacuum chamber. all good now.
also noticed getting intermittent failures on the master window and lock switches. i have pulled and cleaned them once but may need to r&r this year.
