Air Conditioning Circuit Columbia Basin College Automotive Technology.
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Transcript of Air Conditioning Circuit Columbia Basin College Automotive Technology.
![Page 1: Air Conditioning Circuit Columbia Basin College Automotive Technology.](https://reader036.fdocuments.net/reader036/viewer/2022072011/56649e2e5503460f94b1e69a/html5/thumbnails/1.jpg)
Air Conditioning CircuitAir Conditioning Circuit
Columbia Basin College
Automotive Technology
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The Basic Cycle 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 condenser The refrigerant in the condenser is given up to
the less-hot air passing across the condenser coils as it condenses back to a liquid
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Transfer of Heat Relies on Transfer of Heat Relies on Pressure ChangePressure Change
Low Pressure of 21-35 lbs - Temp of 21-28 degrees F
High Pressure of 180-220 lbs - Temp of 88-100 degrees F
Anytime there is a pressure change there is a temperature change
Anytime pressure & temp changes there is a change of state
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Pressure’s Effect on Gases Pressure’s Effect on Gases and Vaporsand 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.
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Refrigerant Changes State Refrigerant Changes State
Low Pressure side - Liquid to a Vapor– Low side tubing is often cool enough to collect
frost or water droplets on high humidity days. High Pressure side - Vapor to a Liquid
– Tubing diameter is often smaller than on the low side
– Hotter than the low side tubing
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Temperature - Pressure Temperature - Pressure RelationshipRelationship
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
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Basic A/C SystemBasic A/C System
Two copper coils– one coil is evaporator– one coil is condenser
Between coils is a compressor Fans
page 68C
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CompressorCompressor
Pulls in low-pressure vapor Pumps out high-pressure vapor Provides a endless cycle of cooling Condenses, Evaporating and heating Raises pressure and temperature of
refrigerant entering condenser to a point where it can transfer heat to outside air through the condenser
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SERVICE VALVESSERVICE VALVES
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A/C Service ConnectorsA/C Service Connectors
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CondenserCondenser
Located in front of radiator Compressor pumps high pressure vapor into
condenser where ram air passing over coils carries off heat
The heat loss causes the refrigerant to become a high-pressure liquid.
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Expansion Valve or Expansion Valve or Fixed Orifice TubeFixed 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 evaporator
Regulates pressure differential between the high and low sides.
Keeps evaporation and expansion of refrigerant and most efficient level.
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EvaporatorEvaporator
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 pressure
Has a tray to collect moisture from fins
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FansFans
One fan to circulate air through evaporator fins
One fan to circulate air through condenser fins
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High Pressure SideHigh Pressure Side
High side includes – Discharge side of Compressor– High Pressure vapor lines to condenser– Condenser– High Pressure liquid lines to orifice valve– Inlet side of orifice Valve
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Low Pressure SideLow Pressure Side
Includes:– Orifice– Low Pressure Liquid lines– Evaporator– Low Pressure Vapor Lines– Suction side of Compressor– Outlet side of orifice valve