UNIT 88 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
88-1) What are the two areas into which electrical troubleshooting can be divided?
88-2) What are the three major tools commonly used to troubleshoot the various
electrical components of a refrigeration system?
88-3) Which tool measures if an electrical potential is present at a switch or a load?
88-4) Which tool measures how much current a load is consuming?
88-5) Explain the groups into which compressor problems can be divided.
Mechanical and Electrical. Mechanical defects are problems that affect
88-6) How can a technician determine if a compressor is not pumping to its rated
capacity?
88-7) What are the three major electrical defects that can cause a compressor not to
operate?
88-8) What is the maximum voltage imbalance of a three phase compressor?
88-9) What does RLA stand for when stamped on a compressor?
88-10) At what cylinder temperature will oil break down inside a compressor?
88-11) What should a technician do after changing out a defective compressor?
88-12) Explain how to test if a current relay is defective using an ohmmeter.
To test a current relay using an ohmmeter:
Remove the relay from the circuit.
Set an ohmmeter to its lowest scale. Zero the ohmmeter (if using an
88-13) Explain how to test if a potential relay is defective using an ohmmeter.
To test a potential relay using an ohmmeter:
Remove the relay from the circuit.
88-14) Explain how to test if a capacitor is defective using an ohmmeter.
To test a capacitor using an ohmmeter:
Remove the capacitor from the circuit.
Discharge capacitor with a bleed resistor or a volt meter.
Set an ohmmeter to its lowest scale. Zero the ohmmeter (if using an
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Make a second test by reversing the leads of the ohmmeter.
If the test shows an open or shorted capacitor, repeat the test on higher
resistance scales to verify the capacitor is truly defective, depending on
the capacitance and the meter used higher resistance scales may needto
be used for an accurate test.
For run capacitors, place one of the ohmmeter leads on a terminal of the
capacitor and one lead on the body. If the ohmmeter reads a resistance
the capacitor is grounded and needs to be replaced. Next, test the other
lead of the capacitor.
88-15) Explain how a technician should manual defrost a frozen evaporator coil.
88-16) Explain a method used to determine the correct operating discharge pressure
of a commercial refrigeration system.
The method used is as follows:
Step 1 – Measure the dry-bulb temperature of the air entering the
condenser. (We will refer to this as the EAT – Entering Air
88-17) Explain a method used to determine if noncondensables are in a refrigeration
system.
The method used is as follows:
Determine the type of refrigerant in the system.
Electrically disable the compressor and allow the condenser fan to operate.
88-18) List some common causes of an evaporator operating with a low superheat
and a high suction pressure.
Some common causes of an evaporator with a low superheat and a high
88-19) A technician should use a short refrigeration gauge on what type of
refrigeration systems?
88-20) List some methods of searching for refrigerant leaks.
Some of the various ways to search for a refrigerant leak are performing a