Hi...unbalanced wheels and tires, tire defects and bent wheels, and loose, worn out suspension parts are the typical causes of vehicle front end vibration at speed. It is also possible that loose, or defective, motor mounts can be a cause...
The AC system could be low on refrigerant. Vans that have rear AC hold much more than a standard system. There are however, many more possibilities. Restrictions in the lines and blend door issues could cause this as well. I...
