Collateral damage (water in ventilation system) from hydrolocked engine

I have a 2007 Nissan Altima that unfortunately was the victim of a recent flash flood incident that despite only 6 to 7 inches of water could not handle the wake of two passing 18 wheelers and hydrolocked the engine. After all was said and done with the insurance, the dealership returned my car within a couple of weeks with a new engine. My question is this: Within 24 hours of gaining back the car, I noted a puddle of water on the floor boards of both sides (in the rear since I park on an incline)of the vehicle. My first thought might have been a plugged ventilation system, but now I’m wondering if the dealership had ever really cleared all the water out of the ventilation system to begin with?

How badly was it flooded? Keep in mind that it’s surprisingly common for HVAC systems to flood due to a plugged evaporator coil drain so the system is probably designed to survive a little flooding.

Check the air handler motor to make sure there’s no water in it. Just use the HVAC system and any remaining water should evaporate.

Nearly everyone discovers water on the floor of his car at some time. Typically it’s due to a leaky seal or else a clogged drain, either in the body or ventilation system. The car is then dried out, the leaks fixed, the drains unclogged, and everything is OK. Your first step should be to find the source of the water; it can be coming in from 'most anywhere.

Assuming the passing trucks kicked up enough of a wake to swamp the motor, likely a lot of water also entered into the fesh air intake ducting that sits right next to the windshield. Once you parked it on a hill, the water could drain out of the ducting. I’d certainly raise the issue with the repair facility and also call the insurer. They can pressure the repair facility to look into the possibility that there is still some water trapped in the ducts.

I’d say it got into the vent air intake the same time it got into the engine air intake.