Is this probably a two-stage oil-free screw compressor, am I right?
The pressure ratio of a stage is the output pressure devided by the inlet pressure.
The inlet pressure of the 2nd stage is the intercooler pressure.
So if the ratio is too high, it means the intercooler pressure is too low.
This could be because of a leak, but most likely (depending on the running hours also) it means there is a problem with your 1st stage – it is not producing enough compressed air.
Please let me know the running hours, intercooler pressure and outlet pressure + temperatures.