Air conditioning to the second

Hello to all, with me now 2 x coolant loss within 3 weeks with unsuccessful leak search until today. After the car was overnight in the workshop for observation in the draining condensate under the passenger door leak agent was detected. Suspect of the workshop is that the evaporator is defective in the interior. I have also come since the failure of the air conditioning a bad smell from the ventilation. Cost of new evaporators are very high, the working time with up to 3, 5 pcs. d. specified. My request: Does someone have a working used evaporator or where do I get a semi cheap new one? I hope for sufficient information, don’t let me hang. With greeting to Alle , Axel