donny79

I put front defroster on this morning, after car was hot I pushed off button, the fan kept running, I get to work turn car off blower motor kept running, I had to go under glove box to disconnect the blower motor fan. Anyone know why this would happen out of the blue?

CaliBenzDriver

> SMART HVAC :
There's a fair chance this is normal.
-- The AAC HVAC module tracks temperature and moisture levels.
It tries to dry moisture from the AC evaporator coil and prevent windshield condensation.

-- The timings for this game are enforced by the F-SAM that should cuts off power when sleeptime is up regardless of rain or thunder, power times out!

-- I like your idea of disconnecting stupid blower to preserve crank battery.


> EASY:
--1-- Without doing extensive investigations... you can try to prevent this condition by switching AC:OFF and using HEAT-only instead .... at least for sanity testing.

--2-- Do yourself a favor, Reboot the car for a chance to refresh soft-cradhed CAN-B members.
An automated watchdog function is missing. It's an understatement to say these systems are not built to be reliable.
Let's not chase our tail with this mad game.... reboot!


> BATTLE TIME:
--1-- When you have time, get scanning for faults and live HVAC data. You will gain insight on what sensor HVAC data is acting upon.

--2-- There are multiple factors that can combine to help HVAC disfunction :

1. Solderless moisture sensor
2. Solderless AAC module
3. Painted footwell GND
4. CAN-B signaling
5. sensor/actuator faults

As you remove disrupting factors, these systems will act well under stressful conditions such as low voltage.

Draining a poorly charged battery to prevent windshield fog is a recipe for chaos. We'll try to help W212 not spoil your holiday spirit.
🤞