[MrE]

I'm personally not aware of any 12v DC/120v AC in-dash radios, it's most likely a standard 12v DC radio. Being intermittent it sounds like a grounding issue or possibly a bad solder sleeve. No telling if the PO has messed with the wiring, so you should trace the wires yourself and verify the wiring. Wire tracers are fairly inexpensive, I currently am using a https://www.amazon.com/dp/B07PJ4T6VQ?ref...tails&th=1. I need all the network functionality because my home has structured wiring for everything low voltage.

I personally have my radio power controlled by my ignition switch, where the ignition switch needs to be either acc or on to power up the radio.