I had this issue, with the furnace board getting wet. The dealer simply created a divider from the furnace vent. The outside exhaust cover had vent louvers facing up so rain got scooped inside. So the divider keeps rain from getting on the board. They said this was a known issue.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package