termastatin 1994 3930 newholland tractor?

It's thermostat - here's a video about changing them on a john Deere - your New Holland will probably be similar.

https://www.youtube.com/watch?v=fwYUzHlFx2w

https://www.reliableaftermarketparts.com/p-37974-thermostat.aspx

https://www.youtube.com/watch?v=yu8nWprsYPI

Good luck...
February 2015