Smoke alarm went off then smelled wires burning for 2 minutes,then I called air man he was booked,so I talked to a retired air man he said go buy some coil cleaner,then turn off unit,clean then rinse off with low pressure water ,repeat it helped ours,cause it said hi on our thermeter,after we cleaned went down 1 degree every hour 99,98,96 86,84,n early morning 74,but then around 630 it would like go up 75 and even on up,so we knew was not fixed yet so we called the air man back in 4 days he was caught up,came next day new switch,it had burnt wires into cooling and heating same time cost 110 dollars,I'm very satisified