I see you have a gs400 as well! Have you replaced an expansion valve in the past? And when you mentioned adjusting the expansion valve, do you mean by rotating the disk looking thing in order to expose the valve?
Also if thats the case, can i simply rotate it by hand while its currently connected, vaccumed and with some freon already contained in the ac system?
My system has been sitting there and luckily chicago currently is experiencing a mild summer so no hot humid weather YET... but I can only hope its as easy as turning a disk