Modes Description. Cadillac Catera 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Catera 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Modes Description

Vacuum Fluorescent (VF) Information Display Panel

The VF panel provides system operating information for the driver.

The set temperature displays in Celsius and Fahrenheit values.

The ° F illuminates for temperature measurements in Fahrenheit. The ° C illuminates when metric units are requested. Depress the driver's TEMP button for at least 3 seconds to switch between F ° and C °.

The OUTSIDE temperature reading displays in the same temperature value (F ° and C °) as the requested interior temperature setting.

The OUTSIDE temperature display - - indicates a failure of the outside temperature sensor.

A freeze warning feature causes the outside temperature display to flash. This feature indicates that the outside temperature is cold enough to encounter ice on the road surfaces.

The AUTO display designates that the system is in the automatic mode.

The defrost and the rear heated window functions display as the appropriate icon. Depress the appropriate buttons to initiate the defrost and the rear heated window functions.

Depress the fan rocker button either up or down to adjust the fan speed. The fan speed icon is not displayed in the AUTO mode. The fan speed is designated by the graduating bars in the manual mode.

The MODE rocker button adjusts the direction of the air flow as designated by the icon displayed on the panel. The arrows show the direction of the air flow. The defog icon appears in the grouping when set.

The AC OFF displays when the A/C system is manually turned off.

The recirc icon displays when the system is manually set to recirculate the interior air of the vehicle. The recirc button controls the function in either the AUTO or the manual mode.

Valve (Door) Actuators

The Heating and Air Conditioning (H-A/C) control system utilizes five electrically operated actuators (stepper motors) and utilizes two vacuum actuators. The stepper motors control the following valves:

•	Control the Driver and Passenger Temperature Doors.

•	Control the Inside Air (Panel) Valve Door.

•	Control the Mode Valve (Floor) Door.

•	Control the Defroster Valve Door.


(1)	Vacuum Tank
(2)	Recirculation Valve Vacuum Diaphragm
(3)	Electronically Controlled Vacuum Actuators
(4)	Heater Water Valve (Hot Water Cut-Off)

The vacuum actuators (3) control the following valves:

•	The interior Air Recirculation Valve (2).

•	The Hot Water Cut-Off Valve (4).

Manually Controlled Functions

The following features apply to the Driver (1) and Passenger (9) Temperature control functions:

•	The driver and passenger temperature control knobs provide a Dual-Zone heating and cooling feature.

•	Depress the passenger knob to change the Dual-Zone mode to the Single-Zone mode.

•	The driver side control overrides the passenger side control in all cases.

•	The temperature controls adjust by an open-ended potentiometer in 2° C increments between 16° C to 28° C and 3° C increments between 29° C to 32° C (Fahrenheit increments are in 1° F steps

The following features apply to the Defrost (3) control function:

•	Push the DEFROST button to deactivate the AUTO function.

•	The AUTO function brings the blower speed to speed three.

•	The AUTO function deactivates the recirculation mode.

•	Push the DEFROST button again to return the system to the previously set mode.

The following features apply to the Rear Heated Window (4) control function:

•	Press the rear heated window button to activate the electrically conductive grid lines bonded to the rear window to defog the surface.

•	The outside rearview mirrors also heat when the rear heated window function is activated.

The following features apply to the Auto (2) control function:

•	Press the driver side TEMP know to set the system to the AUTO mode.

•	The sensors provide input to the H-A/C control to maintain the desired interior temperature when the system is set.

The following features apply to the Off control function:

•	The off control function deactivates the HVAC system. The outside air temperature remains displayed.

•	The system attempts to maintain the previously set temperature without the use of the blower motor or the A/C.

The A/C Off (7) control function deactivates the A/C compressor.

The following features apply to the Fan Speed (5) control function:

•	The H-A/C control uses a resistor installed in the duct downstream of the blower motor to control the blower motor speed.

•	The resistor location promotes a cooling effect.

•	The manual fan speed change over-rides the AUTO setting.

The following features apply to the Recirc Air (8) control function:

•	The recirculation function closes off most of the entrance of outside air.

•	The recirculation function recirculates the interior air.

•	The recirculation function aids in the efficiency of the A/C system by using the cooler inside air instead of the warmer and the more humid outside air.

The Defog (6) control function splits the air equally between the defroster and the floor outlets.

The Bi-Level (6) control function provides outside air flow to the panel with a split to the floor outlet.

The Floor (6) control function provides 100% air flow to the floor outlet ducts.

Automatically Controlled Functions

The following is a list of the automatically controlled functions:

•	The Fan Speed.

•	The Air Distribution.

•	The Recirc Air.

•	The Compressor.

•	The Temperature.

•	The Water Valve. The hot water valve shuts the entry of the heated coolant to the heater core when both the driver and the passenger temperature settings are requesting a maximum A/C. Thus, the cooling efficiency is increased.

Cold Air Purge

The humid air which collects around the heater core inside the air distribution module could cause windshield fogging during a start in cool weather with a still warm engine. A purge routine is programmed into the H-A/C control to prevent this. With coolant temperature at least 16° C (60° F) and with the blower motor and the air distribution in the AUTO mode, the air valves move to guide the airflow away from the windshield. During the first five seconds, while the air valves are moving into position, the blower motor does not run. Then, during the next 30 seconds a low blower motor speed purges the moist air from the system. After that the system goes to the normal operating mode.

Hot Air Purge

Warm moist air can accumulate around the evaporator (from the previous A/C operation and/or from the heat soak from the sun) during engine start up in warm weather. The H-A/C control disables the blower motor for 5 seconds while the mode valves position to divert the air to the floor outlets to divert this undesirable air from the driver's face. The H-A/C control sets the blower motor on low for 30 seconds to purge the air from the module before returning to the AUTO mode after positioning the mode valves.

Air Distribution

Mode Air Flow Distribution

Mode	W/Shield	Panel	Floor
DEFOG	50%	--	50%
VENT	--	100%	--
BI-LVL	--	60%	40%
FLOOR	--	--	100%

HVAC Air Distribution (Front View)


(1)	Temperature Actuator Controlled Doors
(3)	Mode (Floor) Actuator Controlled Door
(4)	Passenger Air Mix Actuator Controlled Door
(5)	Driver's Air Mix Actuator Controlled Door

HVAC Air Distribution (LH View)


(5)	Driver's Air Mix Actuator

HVAC Air Distribution (RH View)


(1)	Temperature Actuator
(2)	Defrost Actuator
(3)	Mode (Floor) Actuator
(4)	Passenger Air Mix Actuator