Subaru R-134A, R-12 Air Flow System, Loyale Vacuum System Mode Control, XT Mode Control System

Page 2

Air Flow System

The purpose of the air flow system is to provide air to the heating, ventilation, defroster, and air conditioning systems.

Control of the air flow is accomplished by four types of systems which are Subaru model specific:

Manual cable - Justy

Manual cable/vacuum -Loyale

Manual cable/electric - Legacy,

Impreza, and XT

Automatic electric - SVX

The mode selector controls the rout- ing of air to the defroster, heater core, air

conditioning evaporator, and the outlet ducts. The temperature control lever adjusts the temperature of the air admitted to the passenger compart- ment and regulates the flow of air through the heater core via the air mix doors. The fan switch controls the speed of the fan and thus the

volume of air that flows through the evaporator and heater cores.

Loyale vehicles have vent control levers which are not a part of the mode oningselector switch. These are manually adjusted by the driver and passenger to

admit or restrict the flow of outside air through side vent outlets.

The Legacy and the Impreza have eight position mode panels while the Loyale and XT have six button panels. The additional VENT mode supplies outside air to the passenger compartment through the dash vents. The flow of vent air may be increased by using the fan, and heated by increasing the temperature control setting. The DEF/HEAT mode switches the A/C com- pressor ON and supplies air flow to the defrost and floor outlets. The remaining mode switches operate similar to other Subaru A/C system controls.

The air flow unit used on Legacy vehicles equipped with manual A/C systems is similar to the unit used on Automatic Climate Control equipped vehicles.

“L” Series Air Flow System Controls

Vent Switches

Loyale Vacuum System (Mode Control)

Legacy/Impreza Mode Panel

Only Loyale vehicles use a manually actuated vacuum operated system to

 

control the position of the mode and circulation shutter actuators.

 

The vacuum system operates the air flow shutters in all Loyale vehicles. Check

 

vacuum to the shutter actuators if the defroster, floor vents, or fresh air vents do

 

Systems

not operate properly. The vacuum system also provides vacuum to the FICD

 

diaphragm based upon FICD solenoid signal, if so equipped.

 

XT Mode Control System

 

In XT vehicles, the electrical mode control system operates the various mode

 

shutters and doors.

 

Electric motors control the operation of the air flow shutters in the XT. The

 

motors operate the shutter actuators through a gear drive and linkage assembly.

 

If the flow of air through the defroster, floor vents, or other vents is insufficient,

Electrical System Operation

check operation of the shutter actuators and switches.

 

A/C Cut System

This system is installed on many 1987 and later model year automatic transaxle equipped Subaru vehicles. The purpose of the A/C cut system is to improve engine performance during full throttle acceleration. Refer to the chart to determine component application for the various models listed.

Note: All sequential MFI equipped vehicles feature

A/C cut systems.

Components

 

Fuel

 

 

 

 

 

 

 

 

 

 

Model

System

Trans

A/C

 

 

 

A/C

 

 

 

 

 

 

 

 

Cut

K/D

K/D

Cut

 

 

 

 

 

 

 

 

Unit

SW.

Relay

 

Relay

ECM

 

TPS

Map

XT / XT6 / ”L”

MFI

 

4EAT

 

 

 

 

 

 

 

 

 

”L”

MFI

3AT

 

 

 

 

 

 

 

 

 

 

TBI

 

 

 

 

 

 

 

 

 

 

Legacy SVX

MFI

 

ALL

 

 

 

 

 

 

 

 

 

Justy Impreza

 

 

 

 

 

 

 

 

 

 

 

 

Justy

Carb

 

ECVT

 

 

 

 

 

 

 

 

 

”L” / HB

Carb

3AT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A/C Cut System

5

Image 2
Contents Subaru Air Conditioning Systems Air Flow System Loyale Vacuum System Mode ControlXT Mode Control System Cut SystemSubaru Air Conditioning Systems Fast Idle Control Device A/C Idle Air ControlManifold Gauges Six Step TroubleshootingQuick Touch Method To connect the manifold gauge set to the system To disconnect the gauge set from service valvesPrecautions Evacuating General PreparationsDischarging Oil Discharging and Refill Procedure ChargingPerformance Testing Test ConditionsPerformance Test Results Standard Compressor Systems

R-12, R-134A specifications

Subaru, a renowned automotive manufacturer, has made significant advancements in its air conditioning refrigerant technologies, particularly in its use of R-12 and R-134A. Understanding these refrigerants is crucial for enthusiasts and technicians alike, as they are integral to Subaru's climate control systems.

R-12, also known as dichlorodifluoromethane, was commonly used in automotive air conditioning systems until the late 20th century. It is a chlorofluorocarbon (CFC) that proved to be highly efficient in cooling systems, offering optimal performance in various conditions. However, environmental concerns over ozone depletion led to a phasedown of its use. Subaru vehicles produced before the early 1990s often utilized R-12, characterized by its stable properties and excellent thermodynamic performance. Despite its effectiveness, the negative environmental impact of R-12 has rendered it obsolete in modern automotive applications.

Adapting to these challenges, Subaru transitioned to R-134A, or tetrafluoroethane, in the 1990s. R-134A is a hydrofluorocarbon (HFC) that does not deplete the ozone layer, making it a more environmentally friendly alternative to R-12. This transition coincided with Subaru's commitment to sustainability and compliance with international regulations. R-134A boasts several advantages, including lower global warming potential and improved efficiency in cooling performance. Its thermodynamic properties provide effective heat absorption, ensuring that Subaru drivers can rely on consistent climate control, regardless of external temperatures.

Subaru has integrated R-134A into its vehicle technology without compromising performance. Newer models utilize advanced HVAC systems that maximize refrigerant efficiency while maintaining comfort. Features such as variable compressor speed control enhance overall system performance, allowing for quicker cooling response and reduced energy consumption. Additionally, Subaru employs meticulous system designs to minimize refrigerant leakage, further supporting environmental initiatives.

The transition from R-12 to R-134A exemplifies Subaru's responsiveness to both performance and environmental concerns. As regulations continue to evolve, it's expected that Subaru will continue to innovate in refrigerant technology, prioritizing sustainability while delivering reliable and efficient climate control for its drivers. As vehicle technology advances, it's clear that Subaru remains committed to adapting its systems for a cleaner, more efficient future.