Hi John,

It sounds like there is something wrong with your pressure switch. There is only one way your compressor 'knows' when to load and unload, and that's through the pressure switch.

If changing the differential settings doesn't give any results, that's another indication that your pressure switch is not working.

I have written a few pages about air compressor pressure switches and how to set and use them. Be sure to check it out.

If the pressure switch is malfunctioning, just replace is with the same or similar model.

The blow-down valve does not control the load unload pressures in any way. What it does, is it blows down the internal pressure during unload (saves energy) and it completely blows down the compressor when it stops (so it can easily start up again).

Good luck!

Cas

I found the problem. Actually the pressure switch is only used for start/stop operation. In this case I am running in modulating mode. There is a load/unload valve located on the rear of the tank with a hose routed directly to the inlet valve. It is adjustable to change max pressure and the diff pressure.

Thanks for your responce

John