Presentation on theme: "Air Conditioning Circuit"— Presentation transcript:
1 Air Conditioning Circuit Columbia Basin CollegeAutomotive Technology
2 The Basic Cycle Heat is picked up by the Evaporator Fins Heat picked up by the liquid refrigerant as it evaporates.Heat-laden refrigerant vapor is pumped by compressor into the condenserThe refrigerant in the condenser is given up to the less-hot air passing across the condenser coils as it condenses back to a liquid
3 Transfer of Heat Relies on Pressure Change Low Pressure of lbs - Temp of degrees FHigh Pressure of lbs - Temp of degrees FAnytime there is a pressure change there is a temperature changeAnytime pressure & temp changes there is a change of state
4 Pressure’s Effect on Gases and Vapors Pressure affects the temperature of gases and vapors by raising it’s boiling point.Compressing a gas or vapor increases its temperature because the same amount of heat is concentrated into a smaller space.The temperature of the gas or vapor can be raised without adding extra heat.
5 Refrigerant Changes State Low Pressure side - Liquid to a VaporLow side tubing is often cool enough to collect frost or water droplets on high humidity days.High Pressure side - Vapor to a LiquidTubing diameter is often smaller than on the low sideHotter than the low side tubing
6 Temperature - Pressure Relationship Heating refrigerant causes it to expand. Different refrigerants have different expansion rates.When confined in a enclosed place, a increase temperature is always accompanied by an increase in pressure.For a given temperature, a corresponding pressure will exist in a container of R-12 or R134a
7 Basic A/C System Two copper coils Between coils is a compressor Fans one coil is evaporatorone coil is condenserBetween coils is a compressorFanspage 68C
8 Compressor Pulls in low-pressure vapor Pumps out high-pressure vapor Provides a endless cycle of coolingCondenses, Evaporating and heatingRaises pressure and temperature of refrigerant entering condenser to a point where it can transfer heat to outside air through the condenser
11 Condenser Located in front of radiator Compressor pumps high pressure vapor into condenser where ram air passing over coils carries off heatThe heat loss causes the refrigerant to become a high-pressure liquid.
12 Expansion Valve or Fixed Orifice Tube Provides a restriction in refrigerant flow which the compressor can build up a pressure in the condenser.Compressor suction lowers pressure in the evaporatorRegulates pressure differential between the high and low sides.Keeps evaporation and expansion of refrigerant and most efficient level.
13 Evaporator Function is opposite of condenser Evaporator coils remove heat and humidity from the air being circulated in passenger compartment.When liquid refrigerant absorbs heat, it again becomes a vapor under low pressureHas a tray to collect moisture from fins
14 Fans One fan to circulate air through evaporator fins One fan to circulate air through condenser fins
15 High Pressure Side High side includes Discharge side of Compressor High Pressure vapor lines to condenserCondenserHigh Pressure liquid lines to orifice valveInlet side of orifice Valve
16 Low Pressure Side Includes: Orifice Low Pressure Liquid lines EvaporatorLow Pressure Vapor LinesSuction side of CompressorOutlet side of orifice valve