A/C System Performance Testing Part 2

A/C Performance Testing A performance test can determine whether the A/C system is functioning properly and if it is not can indicate what is wrong so the system can be repaired.Different vehicle manufacturers specify different methods to conduct system performance checks, but as a guideline, the following procedure may be used.Connect a manifold gauge set as previously described. Hang the… Read More

A/C System Performance Testing Part 1

Automotive Refrigerants The refrigerant used in automotive air conditioning systems from their inception until the early 1990s was a chemical compound called dichlorodiflouoromethane, more commonly known as Freon or R12. R12 is a member of the chemical family known as chlorofluorocarbons(CFCs). Although R12 works extremely well as a heat transfer medium in an automotive air conditioning system, CFCs have been… Read More

Volkswagen Instrument Cluster Failure

Over the years of working on VW’s I have encountered enough instrument cluster failures that I would consider it a common problem. There are a few things you should be aware of before attempting to repair this unit. Don’t Buy Used VW Cluster I have tried this route already and have been burned multiple times. The bad part about it… Read More

Variable Valve Timing Systems

Why Use Variable Valve Timing? Increased Volumetric Efficiency Reduction of Pumping Losses Lower Parts Count More efficient Variable Valve Timing or VVT is common on most engines and is responsible for the elimination of many EGR valves as well as increased performance and fuel economy on many engines. Most systems are lube oil activated and use a control solenoid as… Read More

A/C System Operation

A/C System Basic Principles In order to understand how an A/C system works, we must first understand a few basic principles. The first, and most important principle is that heat always moves toward a state of less heat. This is how an engine’s cooling system works. Heat created by the combustion process in the engine’s cylinders is transferred to the… Read More

Emissions System Diagnosis

The link between vehicle emis­sions and air pollution was first identified by studies that began in California during the early 1940s. By the end of that decade, research­ers determined that the smog above California’s Los Angeles Basin was the result of hydrocarbon and oxides of nitrogen emissions from motor vehicles . As automobile manufactur­ers looked into isolating the source of… Read More

IM Testing Procedures

Inspection/Maintenance (IM) The advances made in engine management and emission control technology over the past two decades have resulted in the steady decline of vehicle pollutants. Unfortunately, while HC, CO and NOx output per vehicle is lower than ever before, emissions reductions have been offset by the extraordinary increase in the number of cars and trucks on the road. However,… Read More

CAN Communications | Network Topology

Network Topology Network Topology refers to the manner in which nodes on a bus are interconnected. The most common automotive network configurations are: Ring or loop Star Ring-star hybrid Bus Tree An understanding of the topology of the vehicle network is critical when attempting to diagnose bus communications errors. The topology of the network can provide clues as to how… Read More

CAN Communications | Vehicle Network Protocols

Vehicle Network Protocols The list below is but a few of the multiplexing systems in use today. Each system has its differences but for the most part they operate in a similar manner. We will take a brief look at each system including lab-scope waveforms of bus communications. Chrysler CCD PCI SCI Ford SCP General Motors Class 2 Chrysler CCD… Read More

Hybrid Vehicle Service Saftey

During the initial introduction of Hybrid vehicles, there were many rumors about the perceived danger of servicing them. While the batteries contain harmful or even lethal energy, proper service practices will render these vehicles safe to service. These vehicles should not be serviced in a careless manner and HV gloves should be worn when called for by the manufacturer service… Read More