Method for monitoring operation of heater element of motor vehicle interior heater based on comparing actual resistance of heater elements against known resistance temperature characteristic

摘要

When in use the heater currents and voltage drops across a heater element or individual groups of elements are constantly measured. From the actual resistance (Raktuell) the heater controller derives the temperature (F1) from a known resistance/temperature characteristic. The controller identifies from the measurements during the warming up cycle whether the resistance value is on the falling (16) or rising (18) flanks of the characteristic. From a knowledge of typical values of the minimum resistance value (Rmin) the controller determines whether or not the heater is defective.