Needless to say, the AC/Heater servo is one of the worst parts on many vintage Mercedes, particularly because its plastic case is prone to cracking. I was therefore wondering if the longevity of these things might be increased by applying 1) a rubberized sealer, like undercoating, to strengthen the case, 2) a flexible metallic heat shield to protect the case from engine heat, or 3) a paint that contains aluminum or other metallic particles, which might do both.

Any opinions on what, if anything, might do this are welcome.

Thanks in advance