Was the Escos switch not different, i.e. four pin opposed to two?

The Escos had dual speed fans opposed to the Sierra's single.

My guess is that this problem has only happened since the "Uprated" switch was fitted?

Reason being is that it closes at circa 90 degrees, as the problem with the original one was that it activated too early and stayed on for too long but from memory the slow speed on the Escos activates around the same temperature.

When driving along, does the gauge read what you know as "Normal"?

Martin