I read most of the thread you linked; it seems that A/C problems on an X5 can start anywhere, at any time, for any reason.

I had a problem with the Bowden cable sticking last summer, not allowing me to get full cold air from the main vents, until I turned the rotary dials all the way, and wedged them that way for a week. After that, my main vents allowed for 40F degree air on a 100F+ day. It was just something I'd not had a problem with on other makes before.

So, reading about the HVAC inter-related components:
like HCV, FSR, Bowden cables, heater core (and other unmentioned problems like the DME shutting down the IHKA controls and blowers if the battery is low, the auxiliary fan problems, the A/C variable compressor faults...the list goes on), makes me glad that my automatic climate problem was so simple to remedy.

I guess that, faced with so many possible causes of HVAC problems on the X5, then starting with a refrigerant top-up might be the logical place to start.

__________________
01 BMW X5 E53,3.0i-5L40E, 7/13/01
topas-blau,Leder-grau,"resto-project car"

Here:
14 Lexus ES350,3.5L-U660E
09 HHR Panel,2.2L-4T45E
04 Chevy 2500HD,6.0L-4L80E
98 GMC Sierra 1500,5.7L-4L60E

Gone:
66 Chevelle Malibu 2dr ht.,327>441c.i.-TH350>PGlide/transbrake
08 Cobalt Coupe,2.2L-4T45E
69 & 75 C10s,350c.i.-TH350
86 S10,2.8L-700R4
73 Volvo 142,2.0L-MT4
72 & 73 VW SuperBeetles,1.6l-MT4
64 VW,1.2l-MT4
67 Dodge Monaco 500 2dr ht.,383c.i.-A727
56 Chevy 210 4dr,265c.i.-PGlide