For fuse locations, check the fuse panel cover label or the owners manual.
If you have neither, go to www.volvocarsus.com
"Register" (no password, just an email address) and then you can see the manual on line.

Follow the path through Owners' Information to Library and select the document you need.

Yes, test the flashers.

Also know that the turn sig. wiring goes to flasher relay via the flasher switch on center console. If a wire falls off or connector at back of flasher switch gets tweaked or otherwise messed up the turn signals can fail.

Flasher relay is clipped to vertical corner frame piece of center console, left side. That is the corner close to driver's thigh, closest towards rear of car.

To access it, remove panel at driver's right foot. One phillps screw, one plastic fitting with big slot. Relay should be clipped to metal rail. It sometimes comes loose and lands under carpet edge. Relay is about 1x1x2 inches. Black, from what I've seen. Only 3 wires, which is unusual for a relay.

You can check fcpgroton.com to see which years 240s take the same relay.
Then you can borrow one from another 240 and test in your car if needed.
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DAMHIK: Don't Ask Me How I Know - - - Sven: '89 245, IPD sways, electric rad. fan conversion, e-codes, 28+ mpg - auto tranny. 500 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).