I have a problem that cannot be figured out by the local mechanic....the AC works on regular AC, but on max AC it blows out the defrost only. The AC switch has been replaced because it had a vacuum leak on it. This fixed the problem long enough for a test drive and a short idle. I read that having the ball joints replaced could have caused this problem. Can anyone help out on this? I have a 2002 F250, 7.3L.

 

Wtf the ball joints

 

That's what Ford-trucks.com's forum was talking about. the vacuum line ending there or something.

 

 

Well if it's a vacuum issue your gonna have to start tracing out the tubes and see if you do infact have vacuum on all lines. It's tedious have fun

 

it"s going back to the shop today. They had it 4 days last week. Wish us luck.

 

When replacing the ball joints you can remove the vacuum lines that run the auto locking hubs. More then likely that is what happened. They did not get them reconnected or broke the line somewhere in that area. Check around the hubs for a disconnected or cracked vacuum line.