Don't work in AC but apparently there is a filter that can be replaced (not cleaned), and you can call Inficon for advice if that does not help (just Google Inficon). If you search in this site for pirani you'll find some other info, like this thread http://hvac-talk.com/vbb/showthread....ghlight=pirani . The 99% isopropyl alcohol may be OK, but I'd want to verify that first...
Hope this is a bit of help...