Thermostatic switch for engine fan control on all versions of the HMMWV (all 6.2L and 6.5L engines). P/N 12338599, also replaces 9705400, 5594181, AD105-503. NSN 5930012377322. Normally closed contacts open on temperature rise approximately 220F.
This switch provides the input signal to the time delay module 12338603.