The toggle switch may be a heater blower fan switch.
Mine was the right most toggle from the driver seat, close to the blower motor, and it wasn’t doing anything. The switch proved faulty upon testing and was replaced with a new similar Lucas style toggle switch, allowing power to the blower motor. It still wasn’t working as the blower motor was also frozen. The motor was freed with penetrating
oil and now works just fine using the switch.
Looking up under the dash from the passenger footwell, the wire from that switch on mine was an easy trace to the heater. Body contortion was reduced some while initially tracing that switch wiring using a light and large extension mirror and cell picture/video.
I assume your switch isn't as likely to be faulty, nor you motor frozen, given the more recent build (unless if donor based), yet sharing my experience with a toggle not doing anything, if helpful.
Best of luck. Brent