OK, I have recently purchased a near flawless 86 300 SDL. I love it, but of course there are a few issues. If anyone could help it would be much appreciated.
1. My AC seems to not want to work. The fan motor works (it kicks on when I turn the key to let the glow plugs warm up), but it does not come on when I start the car consistently. When it does come on, it comes out of the vents near the windshield for a while. The dealership claims it is the fan motor. Any thoughts?
2. I noticed this morning while driving in the rain that the speedometer jumps around quite a bit as the car is shifting gears between 1 and 3 giear. It also seems less sensitive at the bottom of the range as it drops to zero when I am still going 10 MPH.
3. I know this is not in the title, but I wanted to ask any way.

Is there a wiring diagram for the 300 SDL? I need to change out the radio. I have a new head unit on the way, but I haven't the foggiest idea how to wire it.
Thanks so much.