hitachi 120-5 A/C circuit short

Hey everybody, I'm wondering if anyone has a tip on where to start looking for a short in the a/c circuit on a 120-5 hitachi. Symptoms are: -10 amp (I think) a/c fuse blows immediately when installed. -If 20 amp heater fuse is installed fan blows on high and nothing on the fan/ air/ heat controls works or appears to have any power. I am hoping/assuming that these two symptoms have the same solution and thought maybe someone else has experienced the same problem. Thanks, Jamie