Question 1

During a performance test of an air conditioning system how long should you let the unit run and stabilize before taking a vent temperature reading?&#10;A) 2 to 3 minutes&#10;B) 3 to 4 minutes&#10;C) 5 to 10 minutes&#10;D) 15 to 20 minutes

Accepted Answer

It is recommended to let the system run and stabilize for at least 5 to 10 minutes before taking a vent temperature reading. This will ensure that the system has reached its steady state and the readings are accurate. Waiting longer, such as 15 to 20 minutes, is not necessary and may be impractical in some situations. Waiting less than 5 minutes may result in inaccurate readings.

Question 2

When performance testing and air conditioning system the engine should be run at:&#10;A) 800 RPM's&#10;B) 1,000 RPM's&#10;C) 1,200 RPM's&#10;D) 1,500 RPM's

Accepted Answer

When performance testing an air conditioning system, the engine should be run at 1,500 RPM's to ensure the system is operating under a load similar to driving conditions, which provides a more accurate assessment of its performance.

Question 3

During a gauge test of an air condition system your fine the suction pressure high and the discharge pressure low to normal. Which of the following could produce these gauge readings?&#10;A) Defective thermostatic switch&#10;B) Expansion valve held open&#10;C) Expansion valve not opening enough&#10;D) Refrigerant charge low

Accepted Answer

An expansion valve held open would allow too much refrigerant to flow into the evaporator, causing high suction pressure and low to normal discharge pressure.

Question 4

During a performance test of an air conditioning system the discharge line from the compressor should be:&#10;A) Cool to the touch&#10;B) Cold to the touch&#10;C) Warm to the touch&#10;D) Hot to the touch

Accepted Answer

The discharge line from the compressor in an air conditioning system should be hot to the touch. This is because the compressor increases the pressure of the refrigerant, which also increases its temperature, causing the discharge line to become hot.

Question 5

What kind of pressures would you suspect would be the result of a defective compressor?&#10;A) High suction pressure&#10;B) Low suction pressure&#10;C) High discharge pressure&#10;D) Normal discharge pressure

Accepted Answer

A defective compressor often results in high suction pressure due to its inability to properly compress the refrigerant, leading to insufficient pressure drop across the system.

Question 6

Before opening any part of the air conditioning system refrigerant must:&#10;A) Be evacuated&#10;B) Be allowed to cool down to relieve system pressure&#10;C) Be vented to the atmosphere&#10;D) Recovered

Accepted Answer

Refrigerant must be recovered using a recovery machine before opening any part of the air conditioning system. Evacuation may be necessary after the repair is complete, but it is not the first step. Venting refrigerant to the atmosphere is illegal and harmful to the environment. Allowing the refrigerant to cool down is not necessary for opening the system, but may be done for safety reasons.

Question 7

During a performance test of an air conditioning system the suction line from the evaporator outlet to the compressor inlet should be:&#10;A) Cool to the touch&#10;B) Cold to the touch&#10;C) Warm to the touch&#10;D) Hot to the touch

Accepted Answer

The suction line, which carries refrigerant from the evaporator outlet to the compressor inlet, should be cold to the touch. This indicates that the refrigerant is absorbing heat effectively from the air inside the space being cooled, which is its primary function in the air conditioning cycle.

Question 8

During a performance test of an air conditioning system the liquid line from the condenser to the receiver-drier should be?&#10;A) Cool to the touch&#10;B) Cold to the touch&#10;C) Warm to the touch&#10;D) Hot to the touch

Accepted Answer

The liquid line should be warm to the touch during a performance test as it carries refrigerant in a liquid state from the condenser to the receiver-drier. The receiver-drier removes moisture and contaminants from the refrigerant before sending it to the expansion valve. If the liquid line is too cold or too hot, it can indicate a problem with the system, such as a restriction or a refrigerant undercharge or overcharge.

Question 9

What cleaning method would be used for an air conditioning system that is extremely contaminated?&#10;A) Purging&#10;B) Flushing&#10;C) Evacuating&#10;D) Ejecting

Accepted Answer

Flushing is the best cleaning method for an air conditioning system that is extremely contaminated. This is because it involves using a detergent solution and high-pressure air or nitrogen to clean out the entire system. Purging, evacuating, and ejecting may be appropriate for certain parts of the system, but they do not provide the comprehensive cleaning needed for an extremely contaminated system.

Question 10

You are gauge testing an air condition system and the pressures are normal but the driver complains that is not cooling effectively. What could cause this type of complaint?&#10;A) Some air and moisture in the system&#10;B) Low refrigerant charge&#10;C) Slipping compressor belt&#10;D) Frozen expansion valve

Accepted Answer

Air and moisture in the system can lead to inefficient cooling even if the pressures appear normal, as they can cause blockages or reduce the system's ability to transfer heat effectively.

Question 11

Any time an air conditioning system is opened it must have the __________ replaced before evacuating the system.&#10;A) Orifice tube&#10;B) Thermostatic expansion valve&#10;C) Receiver drier&#10;D) Compressor oil

Accepted Answer

The answer of Any time an air conditioning system is...

Question 12

If an air conditioning system must be pressurized of service work it can be safely done with:&#10;A) Oxygen&#10;B) Nitrogen&#10;C) Polyalkylene&#10;D) Acetylene

Accepted Answer

The answer of If an air conditioning system must be...

Question 13

During a gauge test of the air conditioning system you find both the suction and discharge pressure to be high. What could be the possible cause?&#10;A) Some air and moisture in the system&#10;B) Excessive air and moisture in the system&#10;C) Restriction in the high pressure side&#10;D) Refrigerant charge very low

Accepted Answer

The answer of During a gauge test of the air...

Question 14

Identify the incorrect statement in regards to PAG (polyalkylene glycol) oil:&#10;A) PAG oil is hygroscopic.&#10;B) PAG oil is easily mixed with any other refrigerant oil.&#10;C) PAG oil can easily damage paint surfaces.&#10;D) PAG oil should be kept in a clean container to prevent contamination.

Accepted Answer

The answer of Identify the incorrect statement in regards to...

Question 15

During a gauge test of the air conditioning system you find both the suction pressure and the discharge pressure to be low. Which of the following could be the cause?&#10;A) Refrigerant pressure low&#10;B) Refrigerant pressure very low&#10;C) Expansion valve or orifice tube blockage&#10;D) Any of the above could be the cause

Accepted Answer

The answer of During a gauge test of the air...

Deck 10: Trouble Shooting