For 1990-2009 cars

## Control Assembly Description C61 Oldsmobile

The heater and A/C control is the vehicle operator's control point for the manual air conditioning system. The heater and A/C control includes the following components:

• | A rotary knob which selects the system operating modes. The following items are the system operating modes:

- | OFF

- | MAX A/C

- | NORM A/C

- | BI-LEVEL

- | VENT

- | HEATER

- | DEFOG

- | DEFROST

• | A temperature control

• | A fan speed rotary knob

• | A rear defogger switch

### Mode Selector Knob

The rotary mode selector knob on the heater and A/C control assembly controls the following components:

• | The 2 electrical switches

• | The vacuum valve

The electrical switches activate the following components:

• | The blower

• | The A/C compressor

The vacuum valve supplies or vents the vacuum to the vacuum actuators. The vacuum actuators determine the following conditions:

• | The air intake

• | The discharge locations

By supplying vacuum to the actuators in various combinations, the vacuum valve controls whether the air comes out of the following parts:

• | The floor outlets

• | The panel outlets

• | The defroster outlets

The vacuum valve also controls the following:

• | Whether fresh (outside) air draws into the system

• | Whether inside air recirculates

### Temperature Control Knob

The rotary temperature control knob is a potentiometer which sends a voltage signal to the A/C temperature valve actuator. The voltage signal varies according to the temperature knob position.

When the temperature control knob moves fully to the left (COOL), less than 1 volt is supplied to the A/C temperature valve actuator.

When the knob moves fully to the right (WARM), the battery voltage is supplied to the A/C temperature valve actuator.

### Fan Speed Control Knob

The fan speed control knob actuates the fan speed switch inside the heater and A/C control. The fan switch position determines whether current flows to the following components:

• | The blower resistor assembly

• | The blower relay

With the mode selector knob in any position but OFF, the following actions occur:

• | The fan circuit activates.

• | The fan operates at the speed selected.

## Control Assembly Description C67 Buick

The electronic heater and A/C control assembly is the vehicle operator's control point for the electronic air conditioning system. The heater and A/C control includes the following components:

• | Soft-touch buttons for the following system operating modes:

- | OFF

- | MAX A/C

- | NORM A/C

- | BI-LEVEL

- | VENT

- | HEATER

- | DEFOG

- | DEFROST

- | RECIRC

- | UPPER

- | LOWER

• | A blower speed control

• | A temperature control lever

• | The ON/OFF switch located in the heater and A/C control for vehicles equipped with a rear window defogger

Operating mode buttons contain an LED indicator that illuminates when selected. The rear window defogger button also contains an LED indicator.

The heater and A/C control is the electronic air conditioning systems control center. The heater and A/C control sends commands to the system components that control the following functions:

• | A/C compressor operation

• | Air discharge location

• | Air discharge temperature

• | Air discharge blower operation

## Control Assembly Description C61 Pontiac

The heater and A/C control is the vehicle operator's control point for the manual air conditioning system. The heater and A/C control includes the following components:

• | A rotary knob which selects the system operating modes. The following items are the system operating modes:

- | OFF

- | MAX A/C

- | NORM A/C

- | BI-LEVEL

- | VENT

- | HEATER

- | DEFOG

- | DEFROST

• | A temperature control

• | A fan speed rotary knob

• | A rear defogger switch

### Mode Selector Knob

The rotary mode selector knob on the heater and A/C control assembly controls the following components:

• | The 2 electrical switches

• | The vacuum valve

The electrical switches activate the following components:

• | The blower

• | The A/C compressor

The vacuum valve supplies or vents the vacuum to the vacuum actuators. The vacuum actuators determine the following conditions:

• | The air intake

• | The discharge locations

By supplying vacuum to the actuators in various combinations, the vacuum valve controls whether the air comes out of the following parts:

• | The floor outlets

• | The panel outlets

• | The defroster outlets

The vacuum valve also controls the following:

• | Whether fresh (outside) air draws into the system

• | Whether inside air recirculates

### Temperature Control Knob

The rotary temperature control knob is a potentiometer which sends a voltage signal to the A/C temperature valve actuator. The voltage signal varies according to the temperature knob position.

When the temperature control knob moves fully to the left (COOL), less than 1 volt is supplied to the A/C temperature valve actuator.

When the knob moves fully to the right (WARM), battery voltage is supplied to the A/C temperature valve actuator.

### Fan Speed Control Knob

The fan speed control knob actuates the fan speed switch inside the heater and A/C control. The fan switch position determines whether current flows to the following components:

• | The blower resistor assembly

• | The blower relay

With the mode selector knob in any position but OFF, the following actions occur:

• | The fan circuit activates.

• | The fan operates at the speed selected.