Question: I own a 2007 F-150. When I hit the brakes or make a turn, I get a sound like water is sloshing from the passenger-side front, but I can't find any leaks. Any advice?
Answer: First, check the evaporator drain tube. That's where the condensation that forms on the air conditioner's evaporator (under the right side of the dash) drips/drains out of the HVAC case and down to the street. Crawl under the truck and look for a rubber tube at the lower portion of the firewall. Compressed air works best, but if none is available, carefully stick a coat hanger into the tube and try to clear any obstructions (leaves, bugs, etc.). Do not apply too much pressure; you could poke a hole in the evaporator. If water comes pouring out, that's the problem. If the drain tube plugs up again, the fix may require removal of the HVAC case for a thorough cleaning. Another possibility is a water leak in the cab, and you're hearing water splashing in the channels beneath the carpet. Pull up the carpet on the passenger side and stick your hand underneath feeling for any signs of moisture. Last but not least, be sure the coolant system is full. Air in the system can cause a gurgling sound from the heater core, which is right next to the A/C evaporator.
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at firstname.lastname@example.org. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.