Heating, Ventilation, and Air
Conditioning (HVAC)
Presentation
© 2013 General Motors Indonesia
Presentation
2013 Chevrolet SPIN Model Year Update
Heating, Ventilation, and Air Conditioning (HVAC)
Overview
The climate control system regulates the temperature inside the vehicle cabin. The climate
control system also removes humidity from air in the passenger compartment.
All vehicles use a manually operated single zone Heating, Ventilation, and Air Conditioning
(HVAC) system. The HVAC system combines advanced features, such as air filtration, with
efficient operation and purposeful design.
The HVAC system increases driver comfort by adjusting the climate inside the vehicle, and
removing dust and pollen particles from the vehicle’s interior air. By increasing driver comfort,
driver alertness also increases, and driver attention can be fully focused on the vehicle
operating environment. Additionally, some drivers have a lower tolerance to dust and pollen
than others; minimizing the presence of potential respiratory irritants can also increase driver
comfort and alertness.
HVAC Module
Refrigerant System
Vehicles with Air Conditioning (A/C) use R-134a refrigerant and a fixed displacement, beltdriven cycling clutch compressor. The compressor is a piston-type, Delphi model CSP-17. In
addition to the compressor, the refrigerant system includes the refrigerant hoses, condenser,
receiver / dehydrator, thermostatic expansion valve, and evaporator.
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Presentation
Air Conditioning Compressor and Hoses
Within the refrigerant system, refrigerant flows from the compressor to the condenser, where it
is cooled by a thermostatically controlled electric cooling fan. Refrigerant exiting the condenser
flows through the receiver / dehydrator.
Condenser, Radiator, and Coolant Fan Module
The receiver / dehydrator mounts directly to the condenser and contains a refrigerant filter.
Replacing the refrigerant filter involves recovering the refrigerant from the vehicle, removing the
condenser, and removing the plug from the bottom of the receiver / dehydrator. Once the plug
is removed, the filter can be removed from the receiver / dehydrator. To install a new filter,
reverse the removal procedure.
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2013 Chevrolet SPIN Model Year Update
Refrigerant Filter and Condenser
Refrigerant flows from the receiver / dehydrator to the thermostatic expansion valve located at
the evaporator inlet, which regulates the flow of refrigerant into the evaporator. As the
refrigerant flows through the evaporator, it absorbs heat from the passenger compartment. As
the refrigerant absorbs heat, it vaporizes. Refrigerant vapor travels to the compressor inlet,
where the cycle begins again.
Application
Specification
Metric
English
70 ml
2.5 oz
Condenser Replacement
30-40 ml
1.0-1.4 oz
Evaporator Replacement
30-40 ml
1.0-1.4 oz
Total System PAG Oil
Capacity
110 ml
3.7 oz
R134a Refrigerant Charge
500 g
17.6 oz
PAG Oil
Compressor Replacement:
The service compressor for 2013
Chevrolet Cobalt / PM7 is precharged with PAG oil.
Refrigerant and Lubrication Capacities
Compressor Control
To operate the A/C system, the driver presses the A/C button on the HVAC control head. The
HVAC control head sends an A/C request signal to the Body Control Module (BCM).
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Presentation
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2
4
3
1. Body Control Module
2. HVAC Control Module
3. Evaporator Temperature Sensor
4. HVAC Air Inlet Motor
A/C Compressor Control Schematic
The BCM delivers the “A/C On” request to the Engine Control Module (ECM). Upon receiving
the “A/C On” request, the ECM monitors the refrigerant pressure sensor, Throttle Position
Sensor (TPS), Engine Coolant Temperature (ECT) sensor, and engine speed. If all operating
criteria are within preset limits, the ECM engages the compressor clutch by providing ground to
the A/C clutch relay. The ECM cycles the compressor on and off based upon the refrigerant
pressure sensor readings.
Refrigerant Pressure Sensor
With the A/C system running, the HVAC control head uses the evaporator temperature sensor
to monitor the evaporator temperature. If the HVAC control head detects that the evaporator
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2013 Chevrolet SPIN Model Year Update
temperature is less than 3° Celsius (38° Fahrenheit), the control head disables the A/C clutch to
prevent the evaporator from freezing.
Evaporator Temperature Sensor
Passenger Compartment Air Filter
Some vehicles have a passenger compartment air filter that cleans air entering the passenger
cabin. The filter removes pollen and dust. The filter should be replaced as part of routine
scheduled maintenance. To replace the filter, remove the instrument panel storage
compartment (glove box) and remove the filter service lid by depressing the lid retainers. With
the service lid removed, slide the filter straight back. Reverse the removal procedure to install a
new filter.
Service Lid and Passenger Compartment Air Filter
Air Distribution
All vehicles are equipped with a manual HVAC system. To adjust the temperature or airflow
settings, the driver uses the control knobs and switches on the HVAC control head.
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Presentation
HVAC Control Head
Blower Operation
The driver can control the blower speed by setting the blower switch to any of five positions,
including OFF. The blower switch and blower resistor are located on the ground side of the
blower motor electrical circuit. The blower resistor block contains three fixed resistors.
Depending on the blower switch setting, blower motor electrical current will travel through one,
two, or all three resistors. In the high blower speed setting, B+ current bypasses the resistors
and travels directly to the blower motor. In the OFF position, no current passes through the
blower motor circuit.
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Presentation
2013 Chevrolet SPIN Model Year Update
1
2
1. HVAC Control
2. Resistor
Blower Control Schematic
Temperature Control
A pull-pull cable system accomplishes all temperature blend door adjustments. The pull-pull
cable system uses two cables that run between the temperature control knob and the
temperature control cam gear. When the driver turns the temperature knob, the knob pulls on
one of the cables, which pulls on the temperature cam gear, causing the gear to rotate. As the
cam rotates, it moves a lever attached to the temperature door, causing the temperature door to
move within the HVAC case.
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Presentation
Temperature Door Control
The position of the temperature door directs air through or around the heater core. The amount
of air passing through the heater core determines the temperature of the air coming out of the
vents. When the driver turns the temperature knob in the opposite direction, it pulls on the other
cable, causing the door to reverse direction.
Temperature Door
Mode Control
The HVAC system contains three mode doors that direct air to various vents. The vehicle has
five air delivery modes: vent, bi-level, floor, defog, and defrost.
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2013 Chevrolet SPIN Model Year Update
Like the temperature control, a pull-pull cable system controls mode door position. Turning the
mode knob on the HVAC control head changes the mode setting. The mode knob pulls on one
of the cables attached to a mode cam gear, causing the gear to rotate. As the cam rotates, it
moves a lever attached to one of the mode doors, causing the door to move within the HVAC
case. At the same time, the gear portion of the cam / gear drives a second set of cam / gears
that controls the position of the other mode door. Turning the mode knob in the opposite
direction pulls the other cable, causing the doors to reverse direction.
Mode Door Cam
Recirculation Mode
The recirculation mode door can be positioned to allow outside air into the HVAC case, or to
allow air from inside the vehicle to be recirculated through the HVAC system.
The recirculation door is controlled by a two-wire electronic actuator mounted to the HVAC case
and a push-button switch on the HVAC control head. When the driver presses the recirculation
button the HVAC control head supplies battery voltage and ground to the recirculation actuator.
The recirculation door moves from its current position to the requested position. Pressing the
recirculation button a second time causes the HVAC control head to reverse actuator circuit
polarity and move the door back. When the door is in the recirculation position, an indicator on
the button illuminates.
Recirculation Switch
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Presentation
Rear Window Defogger
In all vehicles the rear window defogger activates by depressing a switch in the center of the
blower control knob located on the HVAC control head which triggers the BCM to turn on this
defogger and supply power to the rear defogger relay to heat the window glass.
Rear Window Defogger Switch
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