OSU1984DDS

i own a 1983 rx7 gsl, and the air conditioning system was in proper working order. after some time not using the system(perhaps a month) i went to push in the compressor switch to run the air conditioner a bit and the button will not stay in, it just pops out as soon as i take finger pressure away. the light in the center of the button lights up if i continue to push and hold the button in, the fan also works ok when rotated switch is moved. i checked the fuses and all are fine. i appreciate your time and hope there is an answer out there somewhere. regards,,mike in ohio.