Troubleshooting and Servicing

Six Step Troubleshooting

The following six step method of troubleshooting will save time and effort in the diagnosis and analysis of air conditioning problems. It provides a logical approach to solving the problem, not just treating the symptoms. The steps are as follows:

➊Verify the problem (Operational check) Check that the problem does exist.

Are components inoperable or malfunctioning?

➋Determine related symptoms (Operational check) Identify other symptoms that exist.

Are other circuits and components affected?

Do the related symptoms always occur with the primary symptom?

➌Isolate the problem

Use the split half technique, the wiring diagrams, the troubleshooting trees, appropriate model year service manuals, and manufacturer’s manuals to locate the problem.

➍Identify the cause of the problem Is a circuit grounded?

Proper vacuum not available?

Belt alignment and/or tension improperly adjusted, or is a component defective?

➎Repair and/or replace

Defective wiring, vacuum lines, and components as required.

Confirm proper adjustment of components as required.

➏Verify operation

Check the system to verify that the problem has been solved. Ensure that all system components operate properly under standard operating conditions according to technical specifications.

Also check related systems for proper operation.

Quick Touch Method

An important step in troubleshooting air conditioning systems is to use the quick touch method. Very briefly touch the components and tubing on the high side and the low side of the system. High side components should feel warm or hot to touch, while the low side components should feel cool to the touch. Exercise caution when performing this procedure on high side of the system. The tubing and components may be hot enough to cause minor burns. Do not touch or hold for extended periods of time.

Note: If a component on the high side of the system located before the Thermal Expansion Valve is cool or cold, this is an indication of a restriction.

Servicing

Manifold Gauges

The manifold gauges measure the pressures of the low side or suction side and the high side or discharge side of the system. The gauges are calibrated in “psi for pressure” and “inches of mercury for vacuum”. Note that zero (0) psi is equal to sea level or 14.7 psi, or the pressure at the altitude level at which the gauge is being used.

The gauge set consists of the valve body, the connectors for the low pressure, charge or evacuation, and high pressure hoses, and the gauges. The service valves are infinitely adjustable between fully open and fully closed.

Quick Touch Method

Manifold Gauges

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Subaru R-134A, R-12 manual Six Step Troubleshooting, Quick Touch Method, Manifold Gauges
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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.
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