1990 Mustang LX with Electrical Glitches...(someone help!)

Okay, I don't have all the answers to car problems, but here's a weird one. Sometimes, when I start my car, my signal lamps and heat/ac don't work. I'm thinking of several causes, but I'm still not sure. Anybody else have an idea of what's going on? Oh, and it happens usually when the car hasn't been running for a while. Like if I start it the next morning or something like that. Anyway, any help with this situation would be greatly appreciated. Thanks.

I had a similar problem with my stereo and the solution was to ensure that the two peices of the fuse box weren't separating. all i did was push on it from both sides because the facade had slipped from the box and took some of the fuses with it. i'd be sure to disconnect the battery before i did this with bare hands.