The oil required in most R-134a refrigerant systems is:

• A polyalkylene glycol (PAG) oil.

• A synthetic engine oil.

• A synthetic mineral oil.

• Petroleum oil.

An air-conditioning clutch does not engage the compressor. A voltage measurement shows there is 12 volts at the clutch coil feed wire. Technician A says that the clutch coil could be bad. Technician B says that the clutch coil ground could be bad. Who is correct?

• A only
• B only
• Both A and B
• Neither A nor B

A refrigerant storage container is being tested for static pressure with a manifold gauge and it has been in a 70 degrees (f) room for 6 hours. The pressure in the container is 94 psi. Which of these is LEAST LIKELY to cause this result?

• The refrigerant has a 5% mixture of air blended with it.

• The refrigerant has foreign chemicals blended with it.

• The refrigerant has an 8% mixture of air blended with it.

• The refrigerant container is overfilled by 1%.

Any of these statements about refrigerant system tools are true EXCEPT:

• Separate gauges and other refrigerant handling equipment should be used for different types of refrigerant.

• Manifold gauge sets for R-134a can be identified by unique service fitting connections.

• R-134a service hoses are much bigger because of the high system pressures.

• Proper identification of service equipment and hoses is important to prevent cross contamination of refrigerant.

The compressor clutch diode is being discussed. Technician A says a purpose of the diode is to prevent alternating current from the alternator entering the clutch coil. Technician B says a purpose of the diode is to prevent spikes of high voltage created by the clutch coil operation from damaging delicate electronic components. Who is correct?

• A only
• B only
• Both A and B
• Neither A nor B

Which of these inputs to the engine PCM would be LEAST LIKELY to cause an interruption to A/C operation during a drive cycle?

• Throttle position sensor

• Engine coolant temperature sensor

• Upstream oxygen sensor

• Power steering pressure switch

A refrigerant identifier can tell if there is:

• air in the refrigerant system.
• an excessive refrigerant charge.
• excessive oil in the refrigerant system.
• a low refrigerant charge.

Technician A says that A/C cycling pressure switches are used to prevent evaporator icing on fixed orifice systems. Technician B says that thermostatic deicing switches prevent icing on the condensers of systems that use thermostatic expansion valves. Who is correct?

• A only
• B only
• Both A and B
• Neither A nor B

The filter screen of an orifice tube is covered with aluminum particles. Which of these could be the cause?

• A leaking desiccant bag

• A plugged condenser

• A damaged compressor

• A damaged evaporator

Technician A says that an electronic scan tool can be used to retrieve ATC (automatic temperature control) diagnostic trouble codes from a vehicle. Technician B says that the ATC control head can be used to retrieve diagnostic trouble codes from the engine computer. Who is correct?

• A only
• B only
• Both A and B
• Neither A nor B