My '95 E320 climate control works intermittently. Two of the right 3 buttons work (high and low). When I press the auto button and use the thermostat dial on the left the blower turns on and off as it wants. At first, I thought something was loose and we replaced an old fuse that regulates it, but that didn't work. The problem continues. High and low buttons blow air, but the auto cycle fails. Any suggestions of how to repair it?