I suspect the TXV (expansion valve) has a bad O ring. More common than evaporator failure on a 126. Condensate drains can be replaced with vinyl hose or such. Clean out the openings to the drain a bit, first, to make sure debris isn't clogging them.

Replacing the TXV is a physical job, requiring crowsfoot wrenches, leaning upside down, but, for a young man, not too bad. I'm old and find it not too difficult. You MUST read up, in the archives here, or in the factory service manual if you plan to DIY.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)