My mother called (from out of town) this morning, frantic that the feral cat she brought in for the weekend because of frigid temperatures had gone down an open heating vent. She thinks she heard something at 3:30 in the morning that would confirm this. She's worried about him because he has a lame back leg and she's convinced he's not be able to get himself out.

I live 1/3 of the way across the country, so I can't go help. I told her to call the HVAC people for help. They should probably turn off the heat and build a fire (to keep the house warm).

Any other suggestions? The problem is that he's feral, only lets my mother close, and with other people around is more likely to retreat than let himself be found.