System Outline

Current is applied at all time through the HEATER fuse to TERMINAL 5 to of the HTR relay.

When the ignition SW is turned on, current flows through the GAUGE fuse to TERMINAL 2 of the HTR relay then out TERMINAL 1 to TERMINAL 6 of the blower SW.

1. Heater Blower Motor Operation 

   * Low speed operation

   When the blower SW is moved to the LO position, current flows to TERMINAL 6 of the blower SW then out of TERMINAL 5 to GROUND, causing the HTR relay to turn on. This causes current to flow from the HEATER fuse to TERMINAL 5 of the HTR relay, out TERMINAL 3 to the blower motor, then to the blower resistor, and finally to GROUND, rotating the blower motor at low speed.

   * Medium speed operation (Operation at M1, M2)

   When the blower SW is moved to the M1 position, current flows to TERMINAL 6 of the blower SW and out TERMINAL 5 to GROUND, causing the HTR relay to turn on. This causes current to flow from the HEATER fuse to TERMINAL 5 of the HTR relay, out TERMINAL 3 to the blower motor, then to the blower resistor. It then flows to TERMINAL 2 of the blower SW, and out TERMINAL 5 to GROUND. At this time, the resistance of the blower resistor is less than at low speed, so the blower motor rotates at medium low speed.

   When the blower SW is moved to the M2 position, current flows through the HTR relay to the blower motor, to the blower resistor and to TERMINAL 1 of the blower SW, and finally out TERMINAL 5 to GROUND. At this time, the resistance of the resistor is smaller than at the M1 position, so the blower motor rotates at medium high speed.

   * High speed operation

   When the blower SW is moved to the HI position, current flows to TERMINAL 6 of the blower SW and out TERMINAL 5 to GROUND, causing the HTR relay to turn on.

   This causes current to flow to the HEATER fuse to TERMINAL 5 of the HTR relay out TERMINAL 3 to the blower motor then to TERMINAL 4 of the blower SW and finally out TERMINAL 5 to GROUND, rotating the blower motor at high speed.