Coolant Temperature Signal.

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This signal is supplied to the A/CCM from the instrument cluster, the input being required to:

Provide blower inhibit control , to avoid the system in heating mode delivering cold air when the coolant temperature is below 35C unless DEFROST is selected.
To progressively increase the fan speed up to maximum blower speed during warm up control.
To assist in the control of the outlet temperature.
To avoid possible pump or valve damage caused by ice particles in the coolant.