I had a contractor out today to do a leak detection on my HVAC system. He identified the leak as being in the evaporator coil, and showed me how the pressure of the nitrogen he was using for detecting the leak would quickly leak out of the sytem with just the lineset and evaporator coil being pressurized.
He was using 500 psi for this test. I thought normal pressures during operation were only 250 psi or so. Are coils actually rated for this much pressure?