Protect the condenser from road debris impact
There is one thing I stress to most people about extending the life of their a/c.... put a screen in front of the condenser to catch any rocks or debris before they hit the delicate tubes! This can go a long way in putting off a potentially expensive repair. The same type of damage that chips your windshield can poke a hole in your condenser -- and the condenser is closer to the ground than your windshield. I use 1/2" hardware cloth and stand it off at least an inch from the condenser. This shouldn't reduce much air flow.
Of course this tip doesn't apply to all cars, but I thought I'd pass it on to the people that own cars where the grille is too "open", leaving the condenser prone to damage. This is one condition I can call a manufacturing deficiency.
95 E320 Cabriolet, 131K