Might help? (Closest year I could find.)
http://www.volvowiringdiagrams.com/volvo/Volvo%20Relays/Relay%20Locations%2093%20240.pdf
I was just reading resoldering the aircon relays on 700/900 models often brings them back to life. Since the same is true for the 240 overdrive relay, I'd say it's worth trying for the 240 aircon relay too. i.e. Pop the case off the relay, heat your soldering iron up, wipe the tip with a moist sponge/cloth, touch some fresh solder to the tip, reheat every connection adding a little fresh solder to each point.