/// Check the ignition switch. All electrical switches have a life cycle. Given the year of your car the ignition switch is due. You can unplug the harness from the switch and short the positive position to the run position with a solid wire the same size as the pins on the switch. Then use a jumper to briefly short the start position to the first jumper. The car should crank and run if the switch was the problem. The harness plug is keyed so you can reinstall it blind. There are only two screws holding the switch on.

---Do not spray carb cleaner in any Volvo part unless you have absolute assurance ther are no plastic parts inside. I can't remember but some where I read that the auxillary air valve has plastic parts. Gas may be a safe solvent. I use Gas to clean injectors.