Air Conditioner does not act right "some times"

Our sensor was near a 12 volt overhead light over rear passenger seat. Sometimes it got really chilly before it shut off. It didn't matter what the thermostat said. It was especially the case hen we replaced the front heat pump with a larger one. And since both units were integrated somehow it could get quite frosty on occasion. Had to keep telling wife to turn that light off, she wanted it on to use her laptop and complained about it being cold all the times wrapped up in a blanket.