pfft...newbies...
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It mounts to the left of the evap' coil assy. plate as shown in pic (red circle) originally it attached with a rectangular/shallow stainless steel "upside down "U" shaped plate. or you may use two large washers of an appropriate size. don't crush the sensor capillary tubing or accidentally nick/cut it with the threads of the mounting screws.
it needs to be in firm contact with the back-plate, but again, don't crush the tubing.