the rear blower on my ml will run sometimes when the ignition switch is off, also it will run for very short periods an cycle on and off??
Rear a/c blower on 2002 Mercedes-Benz ML500
sounds like a sticking relay, find the relay/fuse center & tap the blower motor relay when it is running with the key off. if it turns off replace your relay. there could be many other problems but this is simple & easy to test.