Your Dash AC system is NOT all FORD. The Dash system is installed by the OEM Motorhome maker. Including the Defroster and Vacuum system. All Thor does is attach the Vacuum hose to the Ford engine. So, as others have stated, when you have defrost only, you have lost vacuum to the AC control system. That usually means the SUPPLY vacuum hose from the engine was knocked off the round Vacuum reservoir ball. This ball is about 4 inches round and will be on the Firewall accessed from outside close to the Dash evaporator box. There will be 2 hoses, one larger than the other. The larger hose will be the supply from the engine. Pull it off the ball and see if you have vacuum with the engine running. If so then follow the smaller hose to the inside dash control panel and check there. Odds are the supply hose will not have vacuum. with engine OFF, follow that hose to where it goes in the engine. Hopefully you will find the problem. Going to FORD may cost you money with NO FIX. Because most Ford dealerships have nobody that knows and understands RV motorhome Dash AC system controls. If you want to pay to get it fixed, call your local Motorhome RV service centers and ask if they have Tech's that know and understand Motorhome Dash AC control systems. They should have people that know the systems. Here is a link to the most common Motorhome Dash AC supplier from your model year. Doug
http://www.evanstempcon.com/troubleshooting.php
