SOFTWARE GP- 3277405 - Caterpillar

Checking Coolant Contactor Accuracy
In many applications, the accuracy of the temperature contactor used in an alarm or shutoff system is very important. To accurately check the actuation temperature of a contactor, do not use a static water bath. Actuation temperature will be 10°C (18°F) or above the actual actuation point when the contactor is installed in an engine. Even using an agitated glycol bath can produce a 3 to 5°C (5 to 9°F) error.
In order to provide a rate of coolant flow high enough to insure accuracy, contactors should be checked in a running engine in a location with good coolant flow. Refer to the test procedure described in the reference.