My father recently purchased a 2006 Montana. The air in the van is very weak and hardly works at all. He has taken the van in and the mechanic told him someone used stop leak in the lines and it was a product that contained tons of little tiny bb's. The line is plugged somewhere thus causing the problem. He replaced the front expansion valve and that did not fix the problem. Now he has a list of what he wants to replace in order next. I have a pretty good idea that the next steps are to replace the receiver drier and the rear expansion valve. I have no idea where to locate these two parts on the van. I know what they look like and can order them online for around $70. After i replace both i plan on taking the van in and getting the system recharged by a pro and having them run the dye through the system to check for leaks. Thanks in advance for any help.