Hello I have a 1998 E250 that blows AC or heat through defrost vent only Any Idea how to fix this thank you?

 

Is it a gas or diesel engine?

 

Its gas you think it might be the switch if so where would i find the part

 

It could be a vacuum issue, see if you are getting vacuum into and out of the vacuum reservoir. Also check to see if the vacuum lines into the heater control system are ok. Defrost is the default setting with no vacuum applied.

 

Where are the vacuum lines on the Econoline 250 van?