Automotive Service
Modern Automotive Technology
Study Guide for Chapter 75
Pages 1469 - 1492
Heating, Ventilation, & Air Conditioning
65 Points
Automotive Service
1. The term “air conditioning” generally means controlling the
___________________, ______________, and flow of air in the
passenger compartment of a vehicle.
Temperature, Humidity
Temperature, Circulation
Temperature, Direction
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2. A ________________________ system, a ______________ system,
and a ___________________system are used to provide a comfortable
passenger environment in all weather conditions.
Refrigeration
Heating
Ventilation
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3. To learn refrigeration principles, the 3 states of matter, _________,
_____________, and ______ (vapor) must be understood.
Also know that: heat is the controlling factor in the states of matter.
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4-7. Heat always moves from ____________ to ____________ objects
and is transferred in three ways:
___________ is heat transfer through objects touching each other
___________ is heat transfer caused by air moving past surrounding objects
___________ is heat transfer commonly caused by infrared (invisible) waves
From Hotter to Colder
From More Heat Toward Less Heat
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8. The ______________ ________________ ________ (Btu) is the unit for
measuring the quantity of heat transfer from one object to another.
Degrees are our method of measuring heat intensity.
Bonus Thermal Unit
British Thermal Unit
Bahamas Thermal Unit
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9. _______________________ & ____________________ generally refer to
liquid changing into a vapor. Heat is absorbed to make this change.
Absorbing heat boils refrigerant just like absorbing heat boils water in a kettle.
Vaporization & Evaporation
Vaporization & Condensation
Condensation & Evaporation
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10. _______________________, the opposite of vaporization, is when a vapor
changes back into a liquid. Heat is given off when this change is made.
Refrigeration
Condensation
Ventilation
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11. When pressure is applied to a substance, its ________________ increases.
(the inverse is true also)
Temperature
Volume
Displacement
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12. _______________ is the substance with a very low boiling point
that exchanges heat (is the refrigeration medium) in an A/C system.
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13. Both R-____ and R-________ are found in automotive A/C systems.
R-12 is a CFC & is being phased out. R-134a is a HFC
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14-17. Refrigerant goes through four phases during the “refrigeration cycle”:
C) ________________
C) __________________
E) ________________
E) __________________ (vaporization)
Blue = Low Pressure
Red = High Pressure
Condensation
Expansion
Compression
Evaporation
Start Here
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18-21. The four basic parts of the A/C system are the:
C) _________________________________
C) _________________________________
E) _________________________________
E) _________________________________
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22-25. In addition to the 4 basic parts to accomplish the basic refrigeration cycle,
______________________ circulates through the system,
a ____________ (fan) is used to circulate air, (motor & squirrel cage fan)
a ______________-_______ or an __________________ containing
a desiccant, stores and removes moisture from the refrigerant
and finally, some type of thermostatic switch cycles the compressor on &
off to prevent evaporator freezing.
Blower
Refrigerant
Receiver-Drier or Accumulator
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26. A/C’s 4 functions are to ________, _________________, ___________
and _________________ the air.
Cool
Dehumidify
Clean
Circulate
C.
D.
4.
F.
E.
2.
3.
1.
5.
A.
B.
Expansion Valve
Coolant Recovery
Reservoir
Evaporator
Accumulator
Blower Motor
Radiator
Water Pump
Heater Core
Cooling Fan
Compressor
Condenser
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27. VALVES, DUCTS, FLAPS, (moved by either vacuum motors or electric servos)
& SWITCHES are used to direct the air flow under the dash.
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28. The two major divisions of an A/C system are the __________ side and the
________ side.
High Side in the
Engine Compartment
Low Side in the
Passenger Compartment
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29. The high pressure/high temperature side is under the HOOD,
while the PASSENGER compartment is the area where the
low pressure/low temperature side of the system operates.
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30. The A/C compressor is engaged and disengaged by an electromagnetic _____.
Clutch
Crutch
Dutch
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31. A very pure, highly refined, high-viscosity refrigerant _______
circulates with refrigerant for lubrication.
Water
Coolant
Oil
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32. Special high-pressure (250 psi) refrigerant lines & _______ carry the
R-12 or R-134a through the system.
Hoses
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33. The condenser, located in front of the _______________,
transfers heat to the outside, air.
Headlights
Radiator
Back Seat
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34. The receiver-drier may be equipped with a __________ ___________ to
allow observation of refrigerant flow. It always has a desiccant inside to act
as a drying agent, removing moisture from the refrigerant.
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35. Compressors are actually piston pumps, similar to engines, and need a
_________________ to quiet them.
Muffler
Radiator
Balancer
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36. An ___________ tube or an _________________ Valve control R-134a
flow through the evaporator.
Orifice Tube or Expansion Valve
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37. There are many types of switches used to control A/C operation,
both ______ & _______ pressure cutout switches as well as ambient
temperature switches limit operation to prevent system damage.
Low & High
Crashing & Burning
Freezing & Boiling
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38. The heating system uses a small, radiator-like unit called the _________
_______ and the same squirrel cage fan & blower motor as the A/C system
to circulate warm air through the passenger compartment.
Heater Core
Repeater Core
Curriculum Core
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39. HVAC DUCTS & VENTS can be operated by ELECTRIC switches,
mechanical LEVERS & CABLES, vacuum switches and motors or
electronic control units like computers and sensors.
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40. Many vehicles now use a __________________ compartment air filter
known as a cabin air filter.
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ASE-Type Questions
[pages1491 & 1492]
Circle your choice for the correct answer
1.
A
B
C
D
AC theory
2.
A
B
C
D
matter
3.
A
B
C
D
conduction
4.
A
B
C
D
heat transfer
5.
A
B
C
D
evaporation
6.
A
B
C
D
condensation
7.
A
B
C
D
pressure
8.
A
B
C
D
refrigerant
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