On second thought, you may want to cut the end of the hose so that it roughly resembles a mouth - with two 30-45 degree cuts so that when viewed from the side, they form a V. This will probably provide a better hose-phone interface for better suction. Still think the grease may help for a good seal.
When you feel like you have the phone, push it a few more inches in, turn/twist the hose 180 degrees before trying to pull it out. This will better get it around the impasse.
I can’t believe you two brains haven’t had to retrieve something using vacuum or sticky. You SHOULD retire. In addition to all the great ideas given, also do whatever possible to raise the front of the car as much as possible thus causing gravity to assist in the retrieval. If nothing works, leave the phone where it is and get over it!
There are extendable rods with magnets attached that are used in to pick up bolts that have been dropped in hard to reach places. They are quite cheap so if your phone is magnetic you should be able to use it. I suspect that the ductwork is plastic so you don’t even have to see the phone to latch onto it. If the magnet is not strong enough you should be able to get a neodymium magnet for a reasonable price and attach it to a metal rod. These magnets can crush your fingers if they get caught between two of the magnets so they should be able to grip the phone well enough. If the magnet wants to stick to something else using a thin piece of plywood should allow you to slide past any obstacles.
Use your own household vacuum or if not strong enough - a self serve car wash vac. The key is to get some flexible tubing (found at any hardware store) fit over end of vac attachment. Attach by stretching over attachment using se soapy water. This should allow you to get through the bend…without bending your car out of shape. GO SLOW!
If any of you had ever done any housework the answer would be obvious. There is this thing called a vacuum cleaner. It sucks things out of places they don’t belong.
As an experienced body and fender guy for about 6 years or so, among many other things I have done in my career, I would suggest the following, in this particular order.
As someone else mentioned, go to the dealer and find out what the duct in question looks like, and discern where it might be stuck.
It fell in because of Gravity, so trying to use a vacuum to get it out the way it went in will be nearly impossible, so fogeddabout that.
Call your lost phone, if you think it has any battery left, and use a rubber hose like a heater hose held near your ear and use the other end to home in on exactly where it is.
Once you have found it, pull back the carpet to reveal the relevant area, and then repeat the ring test, which will be much more accurate then.
Take a small peanut grinder with a cutting wheel on it to cut a small port in the top of the floor duct, say 4 inches by however wide.
Use a mechanic’s mirror to see where it is, and retrieve it using coat hanger wire or whatever.
If the phone battery is dead, who cares? Phones are so small these days that I bet your rear passengers will never even notice unless you tell them about it.
BTW- My first patent attorney was Satya Pal Asija, who was the first person in the US to be awarded a patent for software. He is a very wise and intelligent fellow.
I like the vacuum and pressure approaches already given. I can only suggest one other thing that might be helpful use floatation simultaneously. Make sure your carpet is up. It should’t take much water.
It’s quite simple. He needs a lipstick camera, a hose, and some sort of strong air pump (preferably one strong enough to make suction that will lift the phone). He then ties the pump to the end of the hose and starts hitting the car with this makeshift flail until it is in small enough pieces that he can find the phone. Having filmed this entire process with the camera, buy a new car using funds uploading the video to youtube (It will of course go viral).
Don’t give up. It is simply a matter of patience. Keep fishing. Like the other sticky retrieval ideas, use a better sticky (3M VHB doublestick tape or the like) wrapped around your fish wire. Keep refreshing the dirty adhesive tape with another layer if it gets too fouled. Best bet to pull it out is the sticky solution. Get a look at the schematic for the duct work if you can.Goodluck.
Like Frumenty , the fifth commenter, I think Pradeep needs to see where the phone is. Instead of renting a fiber optic camera, he can set his digital camera to close-up focus, and try taking photos of the various nooks and crannies under the passenger’s seat. The car seat, that is.
Another way to stay out of trouble would be to tether the camera so that it is not lost, too!
I believe the easiest and probably the best way to retrieve the cell phone would be to remove one of the vents from the dash and install a fire hose. Turn on the water from the hydrant and let the water push the cell phone out from the lower vent. Problem solved.
Bend the end of the hanger into a “J” shape with a throat only as wide as the phone thickness. Push in past the phone. Rotate 90 degrees and pull slowly.
Use a piece of duct tape sticky side out wrapped around a fly swatter. Use another piece of duct tape sticky side in to secure the previous piece of duct tape firmly to the fly swatter. Slide the fly swatter in between the ductwork to retrieve the phone. Guaranteed to work!
You need a magnet on the end of a long stick such as a coat hanger, or long handled surgical clamps. The phone might be composed of some metals that are magnetic. Worth a try anyway.