On my 87 5kq I have A,B,D,E,F,G on channel 07. (page 87.86 in Mr. B) What do others have? I'm starting to think (big mistake) it's the control head because a signal from it shows activation to open all vents (D,E,F). For center vents it should be A,B,C,F,G. I don't have a C, but that's another matter :) Best regards, Geo