Land Rover Repair: electric issues on 1993 nas 110, land rover dealer, vent fan


Question
bought nas 1993 110 earlier this year from used land rover dealer specializing in defenders. the vehicle was redone with rust repair repainting, etc.
since ownership, the vent blower fan to supply air to the cabin and the radio stopped working simultaneously. this occurred while i was turning the fan on and pushing in the a/c button. they both died as i was driving for the first time after the truck had sat for a few weeks.
The radio (the factory original) does not light up i.e  say code, however the red alarm light does flash. the radio will also beep continuously unless you disconnect the battery with the disconnect switch.  this beeping begins around one hour after leaving the vehicle parked.

any help would be appreciated.

Answer
As you may know, my own company Robison Service is also known for Defender restoration work.  I wish I could say, yes, just look at this simple thing, but it's not usually that easy.

The vent fan and radio problem could have a common cause, or they could just be coincidence.  It sort of sounds like the radio has failed, but I'm not sure.  

Remember this truck is 15 years old, and it has probably been totally taken apart and reassembled, so there are more areas things can go wrong.  Not only can you have bad switches and relays, the wire harness itself may have issues especially at all the junctions and grounds.

These are fairly simple rigs - no fancy body computers - but they can eat up time.  You just have to get out the wiring book and follow it through using experience to evaluate the connectors and relays along the way till it's sorted out.

Keep in mind that many trucks have been modified you you can't always trust the accuracy of the electrical diagrams on these Defenders.