HVAC 122 - Refrigeration & A/C Service ICredits: 3
Instructional Contact Hours: 3
Focuses on concepts of common types of domestic refrigerators, dehumidifiers, and portable air conditioners. Develops an understanding of special references involving the essentials of construction of complete refrigeration systems. Presents theory and principles underlying repairing refrigeration appliances and practical shop work through classroom demonstrations and lab experiments. Credit may be earned in one of the following: HVAC 122, RHA 122 or SKPT 122 .
Prerequisite(s): HVAC 121
Corequisite(s): None
Lecture Hours: 35 Lab Hours: 10
Meets MTA Requirement: None
Pass/NoCredit: Yes
Outcomes and Objectives 1: Construct and repair refrigeration sealed systems, fittings, and size ACR tubing.
A. Set up and use an oxyacetylene torch system correctly.
B. Identify ACR tubing, fittings, and sizes correctly.
C. Swag and size ACR tubing to form swaged slip joints to fit tubing the same size, slip joints to be used as couplings, pinch
joints used to connect driers and capillary tubes, and a butt joint pinch joint as used to seal the tubing ends.
D. Design flare joints correctly.
E. Use tub-bending equipment correctly.
F. Use flare and swag tool kits properly.
G. Select and choose the correct drier size and type.
H. Select and choose the correct solders and fluxes by physical properties and temperature design.
2. Identify sealed system components and their functions.
A. Identify and describe the functions of these sealed system components.
1. Evaporator
2. Suction line
3. Compressor
4. Discharge line
5. Condenser
6. Drier
7. Capillary tube
8. Expansion valve
9. Orifice
10. Accumulator
B. Draw a sealed system diagram or design properly.
C. Define how to properly remove and replace these components.
D. Define the term "flood back."
E. Define the term "restriction."
F. Identify the state of the refrigerant and its temperature in each sealed system component.
G. Identify the pressures of the refrigerant in each component of a sealed system and the temperatures they represent.
H. Identify a sealed refrigeration system by its temperature design.
I. Identify a low temperature system by its operating pressure.
J. Identify a medium pressure system by its operating pressure.
K. Define "oil logging" and "oil migration."
L. Identify a low temperature sealed system as used in refrigerators.
M. Identify a medium temperature system as used in dehumidifiers and air conditioners.
N. Operate a low temperature system and record its pressures, temperatures, and correct operation.
O. Operate a medium temperature system and record its pressures, temperatures, and correct operation.
P. Identify different types of evaporators and condensers as a result of lecture and lab work.
3. Demonstrate an understanding of the functions of electrical controls and electrical components used on domestic
refrigeration equipment.
A. Demonstrate the function and application of thermostats, humidistats, pressure switches, water valves, heaters, and motors.
B. Properly test these components using an Ohmmeter, or a voltmeter, or an amp meter.
C. Learn to identify electrical circuits in an electrical schematic.
D. Trace electrical circuits in a schematic wire diagram.
E. Identify the components and circuits in a continuous run time defrost system.
F. Identify the circuits and components in a compressor run time defrost system.
G. Identify the components and circuits in a hot gas bypass defrost system.
H. Identify the components and circuits in a cyclamatic defrost system.
I. Identify lighting circuits in a diagram.
J. Identify split phase compressor motors and circuits using a voltage relay.
K. Identify split phase compressor motors and circuits using a current relay.
L. Identify split phase compressor motors using thermal relay.
M. Identify permanent split phase compressor motors using a capacitor (PSC motor).
N. Identify correct internal motor circuits using an Ohmmeter.
O. Diagnose electrical circuits using a VOM or amp probe.
4. Demonstrate proper refrigerant recovery methods and charging
A. Demonstrate proper recovery methods of refrigerant.
B. Demonstrate proper use of recovery equipment.
C. Demonstrate knowledge of EPA Refrigeration Certification laws.
D. Demonstrate knowledge and mastery of self-contained and passive recovery devices.
E. Demonstrate proper usage of vacuum pumps.
F. Demonstrate knowledge of proper vacuum pump procedures and applications.
G. Identify proper refrigerants and their pressure temperature relationships in a sealed system.
H. Demonstrate methods used to critically charge a sealed system.
I. Demonstrate ability to charge a sealed system using the new 400 refrigerants that include zoetrope's, blends, and Ternary
Blends.
J. Identify knowledge of refrigerant fractionation and glide and ability to use a pressure temperature chart.
K. Identify proper oils for refrigerants.
1. Alkyl benzene oil
2. Mineral oil
3. POE’s or ESTER oils
L. Demonstrate methods of sweep charging a sealed system and the triple evacuation process.
M. Demonstrate ability to charge a sealed system using electronic charging scale.
N. Demonstrate ability to charge a sealed system using a mechanical weight scale.
O. Demonstrate ability to charge a sealed system using a charging station or charging cylinder.
P. Demonstrate ability to leak test a sealed system.
Q. Demonstrate ability to use leak detection equipment to find a refrigerant leak.
R. Identify EPA Refrigerant Certification leak testing requirements.
5. Demonstrate mastery of diagnosing sealed systems problems.
A. Identify the necessary tools to be used in a sealed system diagnosis.
B. Demonstrate mastery at leak identification and repair.
C. Identify leak locations in a sealed system
D. Identify restrictions in a sealed system.
E. Identify partial restrictions in a sealed system.
F. Identify low charge problems in a sealed system.
G. Identify airflow problems in a sealed system.
H. Identify correct running conditions in a sealed system.
6. Demonstrate mastery of diagnosing electrical problems in domestic refrigerators, air conditioners, and dehumidifiers.
A. Identify the proper tools to be used in electric circuit diagnosis.
B. Demonstrate mastery in the use of Ohmmeters/amp meters/voltmeters.
C. Identify shorts in an electrical circuit using a multi-meter.
D. Identify open electrical circuits using a multi-meter.
E. Identify electrical circuit problems using a multi-meter.
7. Write work orders and descriptive sentences describing your service call to the customer, your supervisor, and whomever
might inspect your work.
A. Describe the service problem using short sentences.
B. Describe the solution to the problem using short sentences.
C. Develop short sentences to identify any parts you must use.
D. Develop short sentences describing any warranty the customer might receive.
E. Develop short sentences describing any special adjustments or setting that may be necessary.
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