GM Service Manual Online
For 1990-2009 cars only

The following components, when used in combination, determine the blower speed:

    • The blower resistor.
    • The blower switch.

The blower resistor consists of 3 resistors located in the same housing.

With the blower switch in LO, the following actions occur:

    • The blower circuit uses all 3 resistors.
    • The blower motor runs at the lowest speed.

With the blower switch in M1, the following actions occur:

    • Two of the resistors are in use.
    • The blower motor runs faster.

With the blower switch in M2, the following actions occur:

    • Only one of the resistors is in use.
    • The blower motor runs even faster.

With the blower switch in HI, the following actions occur:

    • None of the resistors are in use.
    • The blower motor runs at maximum speed.