The fogging of gauge lenses on various heavy duty vehicles has been a problem but the evaluation of various solutions has been an intuitive instead of a quantitative process. This paper details the causes, prevention and testing of the fogging of the lens on air-core gauges (indicating units) covered by SAE J1810. The following three areas are evaluated: internal and external sources of moisture and heat that can cause gauge lens fogging, gauge and vehicle design improvements and tests to rank alternate gauge designs for resistance to lens fogging.
