E-Hybrid 92A HVAC (Heater) fan intermittently blowing full hot after rain or car wash

[Tom Rice]

2017 S E-Hybrid:  After driving in the rain or after a touchless or regular car wash, the cabin heater fan would begin to blow full blast hot air intermittently.  No matter the weather. After some research, I decided the first (no cost) items to check were the condensate drain and the sensor at the cabin air filter.  Getting to the sensor was easy and I checked to see it was properly fastened, its connection secure and that it was clean.  That all looked fine.  I wiped it off and closed it up.  The cabin air filter was also fine.

I removed the right side, front wheel, the inner fender liner to access the condensate drain on the firewall.  There is also a rubber plug covering an access hole into the space (tank?) on the firewall.  There was a ton of small leaves and dirt in the drain and the drain completely clogged up.  (I don't know how.  I'm the second owner.)

I took out the rubber drain and the plug and cleaned out the space behind the drain (on the firewall).  (see the photo).  I used compressed air (light pressure) blowing from the plugged hole to the drain to get the debris out.  Aside from the stunning number of fasteners holding the inner fender liner, it was a pretty easy job.

Problem solved.  Super stoked. I'll admit I was originally worried the battery assembly was getting water in it and causing the problem.

 

Anyhow.  Fixed now.  I've had the car washed and driven in torrential rain and no problems.