Testing unloader - purging too frequently

Spray soapy water around compressor, unloader valve, fittings, airbags.
We had similar issue and we were able to resolve it by replacing the unloader valve fitting and air compressor discharge hose/line.

 

If your compressor has another mounting location for a governor, you can remove the port plug and apply shop air there and listen for air leaking out of the intake. If not, you have to unbolt the governor and try. You can also pressurize the wet tank with shop air so the governor hits cut out pressure and listen that way too. Whatever is easier. Another give away of bad unloaders is the rattlesnake sound coming out the purge valve of the air dryer.