Thanks Dave. It was an overheating of the vfd message. As a way to quiet the vfd fan I had wired it to a 45 C thermo switch. When I removed the thermo switch the problem was solved.
This is wrong. This means your VFD is programmed to stop the water pump in case of an error condition. I assume that we’re talking of the water cooling for the spindle? If yes, spindle should be cooled as long as VFD is in “Run” state. For this, PD052 has to be set to “1”: