How to make the blower motor work without keys in skoda fabia mk2?

Hi all, I live in south india, where it is always hot so I even removed the heater core from the cab. Now i am looking a way to make the blower fan work without turning on the key. Yeah it works but still I don’t wanna turn on the ignition for half hour while i wait for someone to come for using the blower fan. I know I can directly get a 12v from the battery kind of dumb thing. But Am looking for the 12V source which turns off after some time like the radio turns off after a while. I am looking for that timed 12V source cause even If I leave the blower fan on by mistake. It won’t drain the battery if the source is cut off after a while. Thank you in advance 🙏🏼.