Patent ID: 7683294

Claim:
A multistage control system of a Positive Temperature Coefficient heater for a vehicle, comprising: (i) a Positive Temperature Coefficient heater that contains heating elements relevant to a first, second, and third stages; (ii) an Electronic Control Unit that is an engine control unit determining whether a driving condition for the first stage of the Positive Temperature Coefficient heater is satisfied with data comprising an engine RPM and a coolant temperature, the Electronic Control Unit outputting a control signal to a first relay, which switches the first stage into an ON and OFF state, for controlling an operation of the first stage of said Positive Temperature Coefficient heater; and (iii) a heater controller that outputs control signals to a second relay and third relay, respectively, for controlling an operation of the second and third stages of said Positive Temperature Coefficient heater, only if the first stage of said Positive Temperature Coefficient heater is in activation via said ECU, wherein said second relay and third relay each switch the second and third stages into an ON and OFF state.