The relay is powered up and activated thanks to a small electrical current. When it is activated, it lets a current that is much bigger than the original one flow through other two outlets. It is used to control the headlights, the rear fog light, the electric fan, etc.
With 70 PSI in system (injected air through gauges ) turned on AC and clutch didn’t engage. I can’t find fuse box illustration to tell what fuses or relay to check.