Car Automotive

Archive for the ‘Air Conditioning’ Category

The compressor is the pump that circulates refrigerant through the system.The suction side of the compressor pulls in refrigerant in a low pressure,low temperature form. The refrigerant is then pumped through the compressor to the discharge or outlet side where it’s compressed, raising its temperature.It’s now ready once more to condense and release heat. The pressurized,heated refrigerant vapor is forced out of the compressor, through the high pressure line, to the condenser.

Basically, all compressors fall into one of two categories: piston type and rotary vane type. As the name implies, piston type compressors have one or more (up to ten) pistons arranged in either an inline, axial, radial or vee configuration.Rotary’vane compressors have no pistons.

Piston type compressors go through an intake stroke and a compression stroke for each cylinder. On the intake stroke, the refrigerant from the low side (evaporator side) of the system is drawn into the compressor. The intake of refrigerant occurs through reed valves. These one-way valves control the flow of refrigerant vapors into the cylinder.During the compression stroke, the gaseous refrigerant is compressed.

This increases both the pressure and the temperature of the heat-carrying refrigerant.The outlet (discharge) side reed valves then open to allow the refrigerant to move into the condenser. The outlet reed valves may be considered the beginning of the high side of the system.

When viewed in its broadest sense, energy takes many forms, manifests itself in many ways and can be transformed from one form to another in many complex ways. But heat is always there in some way. Let’s take a few examples. The sun, obviously, gives off vast quantities of energy, heat being one of the more obvious ones. On a smaller scale, any fire also gives off heat. The connecting rods, crankshaft and drivetrain of an internal combustion engine convert the chemical energy released in the explosion of gasoline vapors into the kinetic energy of the moving automobile, in the process creating a lot of heat because of the friction created by all those moving parts rubbing against one another. And every time the driver applies the brakes to stop the vehicle, the friction generated between the brake pads and rotors, and between the tires and the road, transforms the kinetic energy of the moving vehicle into heat.

But when you hear the word “heat,” do you think of kinetic energy, friction, internal combustion, fires or the sun? Probably not. The first thought that crosses your mind is the palpable effect of heat on your body when you are in close proximity to a heat source. In other words, the word “heat” makes you think of the physiological sensation of being hot. That’s because we humans are pretty sensitive to heat, or the absence of it.

Automotive air conditioning is generally regarded as one of the two most significant contributions by American automotive engineering to the evolution of the automobile (the automatic transmission is the other). At first, air conditioning was an expensive option found only on the most luxurious automobiles.

As time went on, it became more available, and affordable, to the general motoring public. Today, air conditioning systems are such a widely used option that we seldom give them much thought, until they break and we have to fix them. And that’s what this book is all about – how to keep NC systems operating and how to fix them when they break. The heating system has also been included in this volume because it is an integral part of most modern automotive “climate control” systems. In many instances, it’s impossible to work on the air conditioning system without working on the heating system as well. But before we get into maintaining or servicing either system, it’s essential that you know the principles of air conditioning and heating system operation.

Make sure you understand them clearly before you try to maintain, diagnose or repair the air conditioning or heating system in your vehicle. Neglecting the material in this first chapter could get you into trouble later.