The compressor runs and makes air, so the suction box is open allowing air into the screw. Air filter is good. Seperator is good oil filter is good.

The problem is than when the compressor is unloaded the temp builds up and cuts out on over temp. When the compressor is loaded it seems ok and holds its temp.

So I think the oil is not going through the cooler? But why?
Is there a bypass valve?

A friend said it sounds like low sump pressure! But I haven't got the knowledge on compressors to fix it. Please help me find the info I need.__________________
Andy :-)