Jake0147

The little line at the compressor to the governor on the firewall is not from the compressor, rather TO the compressor. It's the signal line that cycles the compressor on and off to match the demand. Disregard that for this diagnosis.

The symptoms you describe do have a commonality. Follow the line that goes from the governor, to a bulkhead fitting on the firewall, continues on towards the driver's side, down the firewall, and back along the frame. ALL of the missing items get air from that line, including the governor. If that line does not receive system pressure from a stoppage (external or internal causes...) then you will first loose the function of all the items mentioned, and second, the air governor will not sense "true" system pressure and therefore will never cycle the compressor off, thereby not limiting the pressure to the rest of the air system that still does have air, at which point the failsafe mechanism kicks in, that being the pressure relief valve on the air tank...

I'd be lying if I tried to guess where in that line the problem might lie, except that it would have to be BEFORE that bulkhead fitting beside the air governor, so start there and work downwards and back, and if there's no external damage or kinking, then I'd expect low spots could accumulate more crud, and the fitting ID tend to be smaller than the line ID by just a touch in general (there are exceptions) so those might be a likely candidate.

Or maybe it's a bad phlegm baffle on the muffler bearing and I'm just smoking opium, but that's where I'd start.