I've noticed at times my HVAC control unit(manual one), will not function aside from the fan speed knob. The buttons and air temp knob light up but their indicator lights do not. Pressing the A/C, Recirc, Rear Defrost or any of the air buttons does nothing. After tapping on it a few times or simply just driving on and giving it a couple minutes the indicator lights will come on and will work fine for the rest of the time. On mine this started happening after we had a few extremely cold days in here during the begging of the year. I've already checked the wiring and all is intact; I took a peek at the pcb board of the control unit as well but with my eyes I did not see any cracked solder joints Anyone had this issue before and fixed it(without buying another unit)? find out which joint was cracked and needed some fresh solder?