Hello!

I am afraid your mechanic is correct; when dessicant debris contaminates a system, it is practically impossible to remove. The only way to get the dessicant out is to replace the components that it can become wedged in (evaporator, condenser, and expansion valve). In addition, most mechanics would install an inline filter kit to trap any tiny particles that may remain after repair.

Of course, the filter/drier which originally contained the dessicant is in need of replacement also.

The usual reason these dessicant bags fail and rupture is because

(1) The system has been allowed to remain discharged for an extended period of time. The moisture in the air that enters a discharged system is absorbed into the dessicant, causing it to swell and rupture.

or

(2) Incorrect refrigerant has been charged into the system. Typically, this is because of someone mistakenly putting R-134a refrigerant into a system designed to operate on R-12. The R-12 dessicant is not compatible with R-134a; a R-134 systems require use of XH-7 dessicant which was not in production when your vehicle was manufactured. If someone in the past attempted to do a "conversion" of this system to R-134 for some reason, and did not replace the filter/drier with one containing XH-7 dessicant at that time, then they should be at least partly responsible for helping to pay to fix the damage.

I hope this is helpful; if so, please click my accept button! Thanks!