Just having similar issues with my old ex MOD 90. Investigation with Multimeter / & fuse replacement amusingly sparked the blower into action when I put the voltmeter across the fan fuse. Dodgy wiring behind the fusebox to be sorted.. 3rd Fuse up from the bottom of the left hand column of fuses...

Thanks, already browsing the great words of wisdom within :-)

Just bought this ex MOD 90 from Rugged Guide, new paint job & service seems in good condition. Looking forward to needing to work on it!