AUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7D – 17
DAEWOO V–121 BL4
COMPRESSOR MAGNETIC CLUTCH DOES NOT ENGAGE
StepActionValue(s)YesNo
11. Remove the ATC Controller from the instru-
ment panel, keeping the wiring harness con-
nected.
2. Turn the ignition switch to ON.
3. Turn the A/C switch to ON.
4. Check the voltage between ground and termi-
nal A11 on the controller.
Is the voltage within the specified value?11–14 vGo to ”Insuffi-
cient Cooling
Diagnosis”Go to Step 2
2Replace the ATC controller.
Is the repair complete?–System OK–
IAUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7D – 39
DAEWOO V–121 BL4
UNIT REPAIR
V5 AIR CONDITIONING COMPRESSOR OVERHAUL
COMPRESSOR OVERHAUL
Refer to Section 7B, Manual Control Heating, Ventilation,
and Air Conditioning System for details of the following
procedures:
S Clutch Coil.
S Clutch Plate and Hub Assembly.
S Clutch Rotor and Bearing.
S Component Locator V5 Compressor.
S Control Valve Assembly.
S Cylinder to Front Head O–Ring.
S Leak Testing (External).
S Pressure Relief Valve.
S Rear Head, Gasket, Valve Plate, Reed Plate, and
O–Ring.
S Shaft Seal Replacement.
7D – 40IAUTOMATIC TEMPERATURE CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
GENERAL INFORMATION
THE V5 SYSTEM
Refer to Section 7B, Manual Control Heating, Ventilation,
and Air Conditioning System,for general information de-
tails for the following:
S System Components – Functional.
S The V5 A/C System.
S V5 Compressor – Description of Operation.
S V5 Compressor – General Description.
SYSTEM COMPONENTS–CONTROL
Controller
The operation of the A/C system is controlled by the
switches on the control head. This console–mounted
heating and ventilation system contains the following
knobs and display:
Temperature Control Push Knobs
1. Raise the temperature of the air entering the ve-
hicle by pressing the top switch, with the red arrow
pointing upward.
2. Lower the temperature by pressing the bottom
switch, with the blue arrow pointing downward.
3. Actuate the air mix door by an electric motor.
4. Vary the mix of the air passing through the heater
core with the air bypassing the core.
Each press of a switch changes the set temperature by in-
crements of 0.5°C (1°F). This is shown in the temperature
window on the function display.
The Function Display
This is an LCD display indicating the status of the control
settings selected. Starting from the left end of the display,
the sections are as follows:
1. Temperature setting – Indicates the temperature set
with the temperature control knob.
2. Auto status – Indicates whether the system is oper-
ating in the full auto mode or the manual mode.
3. Defroster icon – Indicates manual selection of full
defrost mode.
4. Mode – Indicated by icon, the mode chosen by the
system in auto (or by the operator in manual) is
shown by an illumination arrow indicating the air
path.
5. A/C – A snowflake icon indicating whether the A/C
is ON or OFF.
6. Fan speed – Indicates the fan speed by illuminating
a bar based on the segment at the front, for low
speed, and adding additional segments in order up
to the fifth, for high speed.Eight Additional Push Knobs
1. Full defrost – Causes the mode motors to direct all
air to the windshield and aide window outlets for
maximum defrosting.
2. Air intake – Switches between fresh air intake, the
default, and recirculating air. Airflow arrows on the
display indicate the mode in effect.
3. Full Auto Switch – Maintains the set temperature
automatically. In this mode, the fully automatic tem-
perature control (FATC) system controls the follow-
ing:
S The air mix door motor.
S The mode door motor.
S The blower motor speed.
S The inlet air door motor.
S A/C ON/OFF.
4. OFF Switch – Turns the automatic air conditioning
and fan control off.
5. Mode Switch – Allows manual selection of the air-
flow direction.
S Selection is shown on the function display.
S Each time the mode switch is pressed, the next
function is displayed.
6. A/C Switch – Allows manual selection and control
of the air conditioning function.
7. Fan Control Switch – Allows manual selection
among five fan speeds.
8. Defogger Switch – Turns on the electric defogging
heater in the rear window and the outside rearview
mirrors, if the vehicle is equipped with heated mir-
rors.
Pressure Transducer
Pressure transducer switching incorporates the functions
of the high–pressure and the low–pressure cutout
switches along with the fan cycling switch. The pressure
transducer is located in the high–side liquid refrigerant line
behind the right strut tower, between the right strut tower
and the fire wall. The output from this pressure transducer
goes to the electronic control module (ECM), which con-
trols the compressor function based on the pressure sig-
nal.
Wide–Open Throttle (WOT) Compressor
Cutoff
During full–throttle acceleration, the throttle position sen-
sor (TPS) sends a signal to the ECM, which then controls
the compressor clutch.
High RPM Cutoff
As engine rpm approaches the maximum limit, the ECM
will disengage the compressor clutch until the engine
slows to a lower rpm.
