My son's 98 E300 has a bad AC leak. Today I had the chance to add some refrigerant to see what was going on. After getting up to about 1.4 bar of pressure, I turned the car off and heard a very obvious hissing sound from the left front. With a leak detector I was able to determine that the source of the leak is directly beneath the front washer tank...it's a very precise spot that sets off the detector.

Could anyone hazard a guess as to what's leaking and what's involved in effecting repair before we go any further?

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 158k miles
06 E320 CDI "Rutherford", Black on Tan, 177k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 72k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife