Dealer Can't Find AC Leak

A/C leaks can be difficult to locate sometimes, often it can be the method of leak detection used that can be a problem, many opt for the dye leak detector system, this is a fluro dye that is added to the refrigerant and it is visible as a stain when a leak is present, but if the leak is in the evaporator, this will not be sen as it is all hidden in the A/C system under the dash, what I use in your case is a sniffer, this is an electronic detector that gives signal when refrigerant is detected, this sniffer will detect the refrigerant in the air stream coming from the dash vents, if the detector gives a reading, your problem will be with the evaporator unit, try this method next.

Mark (mhpautos)