Name: 
 

Chapter 12



True/False
Indicate whether the sentence or statement is true or false.
 

 1. 

A low-pressure control closes on pressure drop.
 

 2. 

A high-pressure control closes on a pressure drop.
 

 3. 

If a low-pressure switch has opened on a residential air conditioning system, it is usually an indication of a defective low-pressure control.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 4. 

When checking the secondary of a low-voltage transformer with an ohmmeter, if the transformer secondary is open it will read ____ ohms.
a.
infinite
c.
100
b.
0
d.
1000
 

 5. 

When checking a fuse on a 24-volt power supply with a voltmeter, if the fuse is blown, ____ volts will be read.
a.
0
c.
48
b.
24
d.
115
 

 6. 

When an air conditioning system has been pumped down, which component is not isolated?
a.
evaporator
c.
TXV
b.
filter/drier
d.
compressor
 

 7. 

While troubleshooting a residential air conditioning system, the technician reads 24 volts at the compressor contactor coil, but the contactor does not energize. What is the most likely problem?
a.
defective transformer
c.
defective contactor coil
b.
defective contactor contacts
d.
high-voltage fuse blown
 

 8. 

When troubleshooting a residential air conditioning system, the technician reads 24 volts across the high-pressure control. What would be the most likely problem?
a.
defective high-pressure control
c.
defective compressor
b.
dirty condenser
d.
defective transformer
 

Short Answer
 

 9. 

List the four components that make up an electrical circuit.
 

 10. 

List four conclusions that can be made about a residential HVAC system when the fan switch is turned to “ON” and the fan motor starts.
 



 
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