It doesn't always keep heat that we set it on we sometimes have to set it all the way up to 75 just to get above 65 but then sometimes it keeps the heat that we sent it on , at night I have to get up plenty of times because we end up cold it goes as low as 61 when we have it set at normally 70 to 73 we live in the south so normally it don't get so cold that it would have a hugh problem trying to keep up with outside it doesn't even kick on when it gets that low how do I try and fix it