93 Silverado with heat and ac controls and display not working. Buttons are not functioning and the display is also not working. Just replaced the power steering pump. Accidentally ran the battery down while replacing the pump. Charged the battery. Not sure if this is relevant but thought it was worth mentioning. Thanks

I would start buy checking fuses and for power and ground. But this is not the first time that the temp. control unit on this model had gone bad. If you have power and ground then you will have to replace the control head.