Chrysler Repair: Minivan Airconditioner, chrysler town and country, chrysler town and country van

Question
Hello,
I am not sure if you can answer my question, but I appreciate any information you may have.  About 2 weeks ago our 2001 Chrysler Town and Country van airconditioner would only cool in the rear section.  The fans worked in all areas, but no cooling in the front section.  The compressor was cycling on and off so I added two cans of the book recommended refrigerant.  It worked well (cooled in all areas) for about a week and a half, now it is back to cooling only in the rear section, I suspect the refrigerant is leaking.  I am considering filling it again using refrigerant with a stop leak additive.  Do you know if the stop leaks can do damage to the system?  If it would cause more problems than it might fix I won't try it, but thought you might have some ideas on the effectiveness of the stop leak.
Thanks for reading my question,
Dave  

Answer
Hi Dave,
I would have to say that I am not an expert in A/C problems, but let me make one observation. It may be the case that the problem is unrelated to the refrigerant level in the system, but rather due to a problem in the control unit for handling the flow of air in the front cabin. There is a door that controls the temperature of the air by controlling the relative balance between air flow over the A/C evaporator and the heater coils and if that were not doing its job then the air might be by-passing the evaporator even though it is cold. This might be due to an electronic issue (if this is an automatic temp control type of unit) or a mechanical/vacuum leak (if this is the conventional type of unit).
I just offer this as a possibility in case there was not a cause and effect relationship with your earlier addition of refrigerant. I have no experience with the stop leak fluids. I am curious to know how you resolve this so please let me know.
Roland