I just got my setup installed. My air zenith guage worked for about a day and now it reads 76 psi and the tank gauge is at 200 and the pressure switch has shut off the compressors. The gauge funtions with the pressure changes but it seems to need to be recalibrated? Has anyone experienced anything like this? Is there a spec anywhere that I might be able to check the sending unit. I’d assume an ohm meter would work if I knew what was good.
you have to set it up to 220 psi 
do you have the manual of the gauge???
that happes to me with the hornblasters digital gauge, and i set it up and now it reads 400psi…
The only setup is bar or psi. Both are at a low range. I’d guess a bad sending unit. I’ll have to call Rico today.
also check to make sure the sending unit and both the gauges are grounded together not separate.
does that really matter? because I hooked my hornblasters gague up, calibrated it and its off about 5 psi or so.