Maricopa Community Colleges  IMC128   19964-99999 
Official Course Description: MCCCD Approval: 03/26/96
IMC128 19964-99999 LEC 1 Credit(s) 1 Period(s)
Principles of HVAC/Refrigeration
Refrigeration cycle, system components, types and functions of refrigerant compressors. Compressor components, shaft seals, condemnation criteria, compressor change out procedures. Types and function of metering devices. Physical properties, color coding and safe handling of refrigerants, and superheat evaluation and testing procedures. Prerequisites: None.
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MCCCD Official Course Competencies:
 
IMC128   19964-99999 Principles of HVAC/Refrigeration
1. Trace and describe the flow of refrigerant through the refrigeration cycle. (I)
2. Name and diagram specific components of the refrigeration system. (II, III, IV)
3. Describe the types and function of metering devices. (III)
4. List the steps in performing a superheat evaluation and replacement procedure. (IV)
5. Describe the types, components and troubleshooting of refrigerant compressors. (V)
6. List the criteria for condemning a compressor. (VI)
7. Describe compressor changeout procedures. (VII)
8. Describe physical properties of specific refrigerants. (VIII)
9. Explain safe refrigerant handling practices. (IX)
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MCCCD Official Course Outline:
 
IMC128   19964-99999 Principles of HVAC/Refrigeration
    I. Refrigeration cycle
        A. Compressor to condenser
        B. Condenser to metering device - high to low pressure
        C. Metering device to evaporator
        D. Evaporator to compressor - low to high pressure
      II. Components of the refrigeration system
          A. Evaporator
          B. Compressor
          C. Condenser
          D. Primary controls
            1. Thermostats
            2. Humidistats
            3. Pressure controls
          E. Secondary controls
            1. Metering devices
            2. Simple contactor
            3. Water valve
            4. Solenoid valve
            5. Back pressure valve
          F. Safety devices
          G. Pipe layout/liquid line
          H. Suction line
        III. Metering devices
            A. Thermostatic expansion valves (TEV)
            B. Valve parts and function
            C. Construction of valves
              1. Internal equalizers
              2. External equalizers
            D. Proper valve sizing for system capacity
            E. Replacement procedure
            F. TEV sensing bulb replacement
              1. Structure
              2. Operation
              3. Installation procedures
              4. Start up procedures
          IV. Superheat evaluation
              A. Definition
              B. Setting
              C. Adjustment
              D. Testing
              E. Replacement procedure
            V. Refrigerant compressors
                A. Types
                  1. Reciprocating
                  2. Rotary
                  3. Centrifugal
                  4. Screw -type.
                B. Drive methods
                  1. V-belt, motor pulley and compressor flywheel
                  2. Electric, direct-drive coupling
                  3. Internal combustion engines.
                C. Components
                  1. Valves
                  2. Seals
                  3. Drive motors
                D. Trouble shooting hermetic compressors
                  1. Voltage variations.
                  2. Inadequate lubrication
                  3. Inadequate airflow
                  4. Refrigerant leakage
              VI. Criteria for condemning the compressor
                  A. Evaluating the pressure relief valve
                  B. Evidence of a bad compressor valve
                  C. Evidence of a broken or leaking valve
                VII. Changeout procedures
                    A. Causes of motor burn out
                    B. Check oil content acidity
                    C. Safe handling and disposal of contaminated oil
                    D. Liquid and suction dryer replacement
                    E. Hermetic compressor replacement variations
                    F. Reconnect lines
                    G. Refrigerant leaks evaluation
                    H. Reconnect electrical and control circuits
                    I. Recharge
                    J. Recheck, adjust and leak test fittings
                    K. Recheck motor oil for acid residue
                  VIII. Refrigerants
                      A. Types used in cooling systems
                        1. American Standard Safety Code for Mechanical Refrigeration standards American Society of Heating Refrigeration and Air- conditioning Engineers (ASHRAE) classifications and numbers
                        2. Group I characteristics
                        3. Group 2 characteristics
                        4. Group 3 characteristics
                      B. Thermodynamic properties
                      C. Temperature/pressure relationship
                      D. Boiling temperature
                      E. Specific volume
                      F. Superheat Checking procedure
                      F. Enthalpy/total heat/thermal properties
                      G. Calculating quantities
                    IX. Safety guidelines
                        A. Toxicity
                        B. Flammability
                        C. Color Codes of cylinders
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