Just make sure your HVAC system is in the "off" position. This closes the system off from any debris while the truck is parked.
I got bored the other day and read my owners manual cover to cover........some neat stuff in there....LOL
The heater control section gives a description of how to leave the system for different circumstances when the truck is parked. Like to let the truck interior breath, leave the selector in face/floor. If it's dusty or snowing, leave the selector in "off".
Just read your manual for more details.
But even with mine open, I've never gotten suds in the interior.
2001 Ranger Edge - Bright Island Blue3.0L/5-Speed Manual/Supercab/Stepside/Sliding Rear Window/Step Bars/31x10.5 BFG All Terrain T/A's on Factory Chrome Rims/Class III Hitch/Black headlights & Corners/Black Tail Lights/Titanium Chrome Corner & Signal Bulbs/Sylvania Silverstar ULTRA Headlights & Fogs/Ventshade Window Vents/Tonneau Cover/14% Tint/Pioneer Deck w/ 2x12" Pioneer Subs & Clarion Amp/MAC Intake/Leather Seat Covers/Bilstein Shocks/Westin Safari Bar with 6" 130W Blue Tint Fogs/2006 Fender Badging/LED 3rd Brake Light
Too much to list, check out my Cardomain
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