Well that went well. Not
Too big a leak to pull a vacuum to do a leak test and add some dye to find the leak...
Next step would potentially be to re replace all the seals using genuine MB ones so that there's no discrepancy there (I used generic from a selection box matched as best as it possible) and replacing the compressor and condenser. That way, the only unchanged part would be the evaporator. Which would mean also the heater matrix as it's a dash out job...
Sooo... Ho diddly hum pom.
Try and adapt a tyre valve to add some air to system to find the hiss where it's leaking,my money is on the compressor as they are prone to seals failing if left ungassed for long periods
Edit,just seen that you replaced compressor,New part ?