With the auto climate control, the fan speed is controlled with a solid state motor controller. It's more likely something could fail and cause a current draw with the solid state controller than a simple switch and resistor assembly. You might try unplugging the blower motor controller, reinstall the relay and see if your drain goes away. If so, you've identified the part causing the drain.
[edit] I guess you could go one step further and disconnect the signal wire from the blower motor speed control and confirm that doesn't cause the drain to stop. If that did, then it would suggest the DATC module is calling for the blower motor even when the key is removed from the circuit. One concern I have now that I look at the wiring diagram more closely is the blower motor relay coil only gets power with the key in the Run position.
The source for the switched side of the relay is hot all the time, but if the relay is working, it should be cutting power to the speed control once the key is removed. The next step maybe needs to be confirming that power to terminal 86 of the relay is not present when the key is off, then try swapping the relay with another one. If you're comfortable reading wiring diagrams, send me a private message with the request and an e-mail address for you and I'll send you the 4 PDF pages.
-Rod