Constant Power to Fuse 20

[downforce22]

I went to start my 318is and found the battery dead. Strange since I have driven the car for over a year with no issues.

After I got it going again and went to park, I noticed the HVAC fan was still running even with the ignition off. After poking around some more I found the heater relay clicking when adjusting the interior cabin temp.

I pulled fuse 20 for now which turned off the fan and relay from getting power, but what could be causing this drain?

What should I check first?

[Das Delfin]

I don't have a shortcut, but if you want to troubleshoot methodically, try this

If you download the ETM from wedophones.com (google search it with your model year) you will find a page labeled "fuse 20 detail" which shows all the circuits fuse 20 protects. My guess is one of those circuits is shorting its "hot on ignition" lead to a nearby "hot at all times."

try isolating each one of those modules by unplugging them and see if fuse 20 still has constant power.

[ELVA164]

Fuse 20 is power to the blower motor and air conditioning, through relay K7 (which is an unloader relay). It's possible the relay may be sticking. Try swapping another relay with the same part number and see if anything changes.