section 2 A/C quiz

An air conditioning system should be pumped down (evacuated) for a minimum of ____ minutes.

30 min

On a vehicle equipped with front and rear A/C dual evaporator system, the front evaporator cools properly, but the rear evaporator is warm. Which of the following is the most likely cause?

A stuck open rear expansion valve.

Select all the answers that apply. Before attempting to service an automotive air-conditioning system consider which of the following? Is the vehicle worth fixing? Do you have the proper tools and equipment to service the system? Does your diagnosis make sense based on customer complaint? Listen to customer complaint.

Do you have the proper tools and equipment to service the system? Does your diagnosis make sense based on customer complaint? Listen to customer complaint.

Most original equipment manufacturers use what type of lubricant in their R-134a systems?

PAG

All of the following are reasons why a flooded evaporator will not cool well, EXCEPT:

The refrigerant vaporizes too quickly.

All of the following statements about system evacuation are true, EXCEPT: Vacuum pump efficiency is increased at higher altitudes. Water boils at a lower temperature at higher altitudes. At high altitudes, ambient temperature must be raised for the vacuum pump to efficiently remove moisture. Running the vehicle engine will raise the temperature of the underhood components.

Vacuum pump efficiency is increased at higher altitudes.

During a refrigerant system performance test it is noticed that both high-side and low-side pressure readings are about the same. Which of the following could be the possible cause?

a faulty compressor

While a technician is performing an A/C system performance test, it is determined that the low pressure gauge is reading in the vacuum range. This reading could be caused by ___________.

a restricted expansion valve

If a system has a thermostatic expansion valve, it will also have all of the following parts, EXCEPT: an accumulator a compressor a condenser a receiver-drier

an accumulator

At highway speed the A/C system cools normally, but performs poorly during around town stop and go driving. What is the most likely case of this condition?

an open electronic cooling fan relay

Technician A says in an H-block valve the temperature sensing sleeve (bulb) is internally located in the evaporator outlet passage of the valve. Technician B says the operation and function of the H-valve, or block valve, are essentially the same as the thermostatic expansion valve (TXV). Who is correct?

both

Technician A says that the A/C system may be charged through the LOW side when the system is operating. Technician B says that the A/C system may be charged through the HIGH side when the system is off . Who is correct?

both

A flooded evaporator can cause damage to the _____________.

compressor

O-rings will not usually leak if they are reused.

false

Refrigerant vapors are lighter than air.

false

To replace refrigerant oil the compressor drain plug is removed.

false

When the air conditioning system is operating, the suction line should feel hot to the touch.

false

When making system repairs, install the receiver-drier or accumulator __________.

last

An undercharged system will show which of the following gauge readings?

low side, low; high side, low

Refrigerant leaves the evaporator as a __________________.

low-pressure vapor

What could happen if the evaporator pressure becomes too low?

moisture will freeze on the evaporator surface restricting air flow

A technician determined that all the refrigerant had leaked out of the A/C system. Technician A says that the low-pressure cycling switch must be replaced before the system can be recharged. Technician B says that the low pressure cycling switch should be adjusted before the system can be recharged. Who is correct?

neither

Desiccant is being discussed. Technician A says both R-134A and R-12 refrigerants use the same desiccant. Technician B says the desiccant in an accumulator can be replaced without replacing the accumulator. Who is correct?

neither

Technician A says a receiver-drier is used in systems with a fixed orifice tube. Technician B says the receiver-drier separates the high and low side of the system. Who is correct?

neither

Technician A says that the thermostatic expansion valve may be located anywhere between the evaporator outlet and the compressor inlet. Technician B says that fixed orifice tubes sizes can be interchanged to improve system performance. Who is correct?

neither

Select all the answers that apply. Most vendors will not honor the warranty on a new or rebuilt compressor unless the ____ is replaced at the time of service. receiver-drier expansion valve accumulator blower motor

receiver-drier accumulator On an expansion valve system the valve opens and closes in relation to ______ temperature and pressure.

Once the refrigerant from the air conditioning system has been recovered, which of the following should the technician do?

record the amount of refrigerant oil removed from the system

Select all of the answers that apply. Most air conditioning service can do _____________.

refrigerant recycling, system evacuation, refrigerant recovery

Before installation: Technician A says that refrigerant system O-rings should be coated with new refrigerant oil. Technician B says refrigerant system O-rings should be coated with a sealant. Who is correct?

tech A

Technician A says that the electronic leak detector probe should be held directly against a suspected leak area during a leak test. Technician B says that the electronic leak detector requires routine calibration and probe tip inspection and maintenance. Who is correct?

tech B

Technician A says that the evacuation process will remove dirt and debris from the refrigerant system. Technician B says that the evacuation process will remove moisture and air from the refrigerant system. Who is correct?

tech B

Technician A says the amount of refrigerant flowing through an orifice tube is controlled by a remote sensing bulb. Technician B says the orifice tube is located in the liquid line between the condenser outlet and evaporator inlet. Who is correct?

tech B

On an expansion valve system the valve opens and closes in relation to ______ temperature and pressure.

the evaporator

During initial system evaluation an unknown refrigerant is identified. Which of the following should a technician do?

treat it as a contaminated refrigerant

If the evaporator is starved, superheat is very high.

true

Moisture in a refrigerant system may cause intermittent poor system performance.

true

On a cycling-clutch system, the desired average temperature of the evaporator should be about 35F (1.7C).

true

The electronic (halogen) leak detector is the most expensive and sensitive of all leak detection devices.

true