Its amazing how sloppy the fit between the vacuum tubing (which on mine is about 1/8" o.d. and color coded red, white, blue, yellow, green, black, with clear plastic nipples to connect to the device @ ea. end) and the dash switch nipples. They slide on/off the dash switch w/almost no effort, as frequently reported here on iRV2.
I'm gonna get a new dash radio/CD... some day soon to replace the $3 unit WRV used. When I have the old radio out there will be much better access to the vacuum switch connections & I'll safety wire the clear plastic to the switch nipples or maybe put a small piece of glue-type shrink tube on the nipple to make a tighter fit. I have one setting (AC on feet & in face) where the vacuum runs constantly & that'll be a good time to attack it.
Also while poking around I found that the seal between the plastic blower shroud & front bulkhead isn't made well for about 4" (where some one WRV'd* the fastener), so I taped it shut to regain lost efficiency. I can also see one of the blower output spiral plastic ducts is nearly smashed w/its current routing, and that could be easily rerouted w/slightly better access.
*WRV'd: to power the fastener till it strips or the plastic part under it is wrecked. Motorhomers find many WRV'd fasteners over time.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project