Automotive AC Performance Assessment

What is the primary purpose of using a manifold gauge set in automotive AC system pressure testing?

• To measure engine oil pressure

• To measure refrigerant pressures in the AC system

• To check battery voltage

• To test tire pressure

Which unit is commonly used to measure the temperature at the AC vent during a performance test?

• Volts

• Degrees Celsius or Fahrenheit

• Pounds per square inch

• Amperes

What color is typically associated with the low-pressure hose on a manifold gauge set?

• Red

• Blue

• Yellow

• Green

Which tool is most appropriate for measuring the temperature of air coming from an automotive AC vent?

• Infrared thermometer

• Tire pressure gauge

• Multimeter

• Hydrometer

A technician observes that the high-side pressure is much higher than normal during an AC performance test. Which of the following could be a possible cause?

• Low refrigerant charge

• Blocked condenser

• Faulty blower motor

• Open expansion valve

If the temperature at the AC vent is not as cold as expected, which of the following steps should a technician take first?

• Replace the compressor immediately

• Check the refrigerant pressures using a manifold gauge set

• Add more refrigerant without testing

• Replace the cabin air filter

During a performance test, the low-side pressure is below specification and the vent temperature is higher than normal. What is the most likely cause?

• Overcharged system

• Undercharged system

• Faulty blower resistor

• Blocked heater core

A student is asked to compare the temperature readings at the AC vent before and after running the system for 10 minutes. What is the main reason for this procedure?

• To check for electrical faults

• To ensure the system reaches stable operating conditions

• To test the alternator output

• To measure engine coolant temperature

• Yes, the pressures and vent temperature are within normal range

• No, the high-side pressure is too low

• No, the vent temperature is too high

• No, the low-side pressure is too high

• Add more refrigerant

• Inspect for possible overcharge or condenser airflow restriction

• Replace the compressor immediately

• Ignore the readings and retest later