You might consider breaking the output line from the compressor and fitting it with a coupling to connect it temporarily to a shop compressor or air tank,just to see if the brakes will function. If that's a go,it might be a good idea to incorporate the air hose coupling into the system for such emergencies in the future. (Not to mention it'll be useful for filling a low tire or blowing all the dirt out of the cab a couple of times a year.)
Speed


1954 GMC 350
1957 GMC 1/2 ton
1962 Chevy C-30
1952 Chevy 6400 dump bed project truck
'98 Harley FLSTC
'66 Pontiac Catalina
'76 Chevy 1 ton Duallie
'84 Bronco II
'78 Dodge W-200
'81 Toyota 4X4 truck