Chapter 7&8 A/C

The sensitivity of the electronic leak detector is __________per year.

0.15 ounce (4 grams)

The maximum moisture content allowable in new refrigerant is _________.

10 ppm

In Denver, Colorado, water (H2O) boils at a temperature of ____________.

206.2°F (96.78°C)

The symbol _________(English) is used to denote a vacuum pressure.

Hg (mercury)

A technician is diagnosing a system with a poor cooling complaint and both the high-side and low-side pressure readings are much higher than normal. Technician A says that this could be the result of leaves or debris blocking air flow through the condenser. Technician B says that the vehicle's air-conditioning system may be undercharged. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

a. A only

Technician A says that comparing the temperature-pressure relationship of recycled refrigerant is a reliable method for finding non-condensable gas contamination. Technician B says that if the recovery tank pressure is higher than the temperature-pressure relationship chart indicates, the refrigerant is OK to use. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

a. A only

Technician A says that fluorescent tracer dye is easily detected using an ultraviolet lamp. Technician B says that the dye should be removed from the system after leak detection. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

a. A only

Vacuum pump efficiency is being discussed. Technician A says that vacuum pump efficiency is greatest at sea level. Technician B says that altitude has little or no effect on vacuum pump efficiency. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

a. A only

During a refrigerant system performance test, the high-side pressure instantly goes over 370 psig when the compressor is engaged. Which of the following is the most likely cause? a. An overcharged system b. An undercharged system c. Moisture in the system d. Expansion valve stuck open

a. An overcharged system

A low refrigerant condition is indicated by: a. Both high and low side pressures below normal b. High side pressure normal and low side pressure low c. Both high and low side pressures above normal d. Low side pressure normal and high side pressure low

a. Both high and low side pressures below normal

Which of the following could cause very low pressures on the low side of a system equipped with an expansion valve? a. Expansion valve stuck closed b. Expansion valve stuck open c. Compressor valves not sealing d. Compressor clutch inoperative

a. Expansion valve stuck closed

All of the following could cause low side pressure to be lower than normal except: a. Poor airflow across the condenser b. System undercharge c. Faulty metering valve d. Poor airflow across the evaporator

a. Poor airflow across the condenser

High high-side pressure may be caused by excessive _________ , oil, or __________ in the system.

air, refrigerant

An R-134a system has excessively high low-side and normal to low high-side system pressures. Which of the following is the most likely cause? a. A restricted expansion valve b. A defective compressor c. Restricted air flow across condenser d. The refrigerant system is overcharged

b. A defective compressor

An R-134a thermal expansion valve system contains the proper refrigerant charge. During a system performance test, the low-side gauge reading and the highside gauge reading are in the high range and the system has poor cooling performance. Which of the following is the most likely cause? a. A restricted airflow across the evaporator b. A restricted airflow across the condenser c. An expansion valve stuck open d. A malfunctioning compressor

b. A restricted airflow across the condenser

Technician A says that a restriction in the suction line will cause excessive high-side pressure. Technician B says that a restriction will result in a pressure change, usually marked by frost or ice. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

b. B only

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? a. A only b. B only c. Both A and B d. Neither A nor B

b. B only

Technician A says that the minimum pressure recommended for leak testing an R-12 system is 60 psig (414 kPa).Technician B says the minimum recommended pressure for leak testing an R-134a system is 50 psig (414 kPa).Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

b. B only

Technician A says that tobacco smoke will not affect refrigerant leak detection. Technician B says that an electronic halogen leak detector is the best method of leak detection. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

b. B only

Technician A says that when testing for a refrigerant leak, the electronic leak detector probe should be held against the suspected leak area. Technician B says that the electronic leak detector requires routine calibration and probe tip maintenance. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

b. B only

The high- and low-side pressures may be normal or slightly less than normal based on ambient air temperature. If the refrigerant system is not functioning as designed, the following items should be checked for proper operation, EXCEPT: a. Air duct delivery problem b. Refrigerant system slightly overcharged c. Refrigerant gas contamination d. Refrigerant system slightly undercharged

b. Refrigerant system slightly overcharged

An R134a recovery tank pressure is determined to be 115 psig at 85°F. What does this temperature-pressure relationship indicate? a. The recovery tank is contaminated with moisture. b. The recovery tank is contaminated with air. c. The recovery tank is overcharged. d. The recovery tank is at normal operating pressure.

b. The recovery tank is contaminated with air.

After a repair that required opening the refrigerant system the system should be evacuated (pumped down) for a minimum of how many minutes? a. 5 minutes b. 10 minutes c. 30 minutes d. 60 minutes

c. 30 minutes

Check My Work During a system performance test, the low-side gauge reading and the high-side gauge reading are about the same. Which of the following is the most likely cause? a. An overcharged system b. Moisture in the refrigerant system c. A malfunctioning compressor d. A restricted expansion valve

c. A malfunctioning compressor

During a performance test, both high and low pressures are above normal. Technician A says insufficient airflow across the condenser may be the cause. Technician B says there may be too much refrigerant in the system. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Fluorescent leak detector scanner solution is being discussed: Technician A says once introduced into the system, it cannot be removed. Technician B says a ultraviolet light is required for detecting a leak. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that a gauge reading of 21 psig (145 kPa) corresponds to an R-12 evaporator temperature of about 20°F (-6.7°C).Technician B says that a gauge reading of 21 psig (145 kPa) corresponds to an R-134a evaporator temperature of about 23.5°F (-4.7°C).Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that a liquid line restriction has the same general symptoms as a suction line restriction. Technician B agrees, adding, "An undercharge of refrigerant also has the same symptoms." Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that a sight glass is often found in an R-12 system. Technician B says that a sight glass is seldom found in an R-134a system. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that a standing vacuum test may be held to check an air-conditioning system for leaks. Technician B says that a standing vacuum test does not reveal how many leaks there are in the system. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that a system is contaminated if it contains more than 2 percent of a foreign substance. Technician B says that air is considered a contaminant if it exceeds 2 percent of the system capacity. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that air is a non-condensable gas. Technician B says that air collects in the evaporator during the OFF cycle of the air-conditioning system. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that if R-134a evaporating temperature is 30°F (-1.1°C), the gauge pressure should be about 26 psig (179 kPa).Technician B says that a low-side gauge pressure of 26 psig (179 kPa) indicates a refrigerant evaporating temperature of 27°F (-2.8°C) in an R-12 system. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that low suction and discharge pressure may indicate a low refrigerant charge. Technician B says that low suction and discharge pressure may indicate a restriction in the system. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that moisture in the system can cause poor or no cooling. Technician B says that moisture in the system can cause harmful acids. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that service ports may be a source of leaks. Technician B says that hose connections are sometimes a source of leaks. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that special electronic leak detectors are available that are used for halogen gases. Technician B says that there are electronic leak detectors available that will detect CFCs as well as HFCs. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

Technician A says that the air-conditioning system can be charged from the low side while the system is running. Technician B says that the air-conditioning system can be charged from the high side while the system is not running. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

When an air-conditioning system is opened for repairs or service, there is a possibility that __________ will enter system. a. Air b. Moisture c. Both A and B d. Neither A nor B

c. Both A and B

When performing a system performance test, technician A measures the temperature in front of the radiator. Technician B measures the temperature of the center AC vent. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

c. Both A and B

All of the following may cause a low-pressure gauge to go into a vacuum, except: a. Clogged screen in the metering device b. Clogged screen in the accumulator c. Clogged screen in the receiver-drier d. Thermostatic expansion valve stuck closed

c. Clogged screen in the receiver-drier

During a refrigerant system performance test the following results are recorded: outside ambient temperature of 90°F, high-side gauge reading of 145 psi, and low pressure gauge reading of 14 psi. What is indicated by these results? a. Faulty refrigerant compressor b. Normal refrigerant system operation c. Low refrigerant levels d. A restriction on the high side of the refrigerant system

c. Low refrigerant levels

A customer complains of poor air-conditioning cooling performance. During a system performance test, the low-side gauge reading is 50 psig; the high-side gauge reading is 310 psig; and the ambient air temperature is 81°F (27.22°C). What is the least likely cause of the above results? a. Restricted airflow through condenser b. Refrigerant overcharge c. Refrigerant undercharge d. Overcharge of refrigerant oil

c. Refrigerant undercharge

Temperature and pressure comparisons are a standard practice to determine all of the following, except: a. System change levels b. Superheat c. Subheat d. Subcooling

c. Subheat

The most accurate method for measuring the effectiveness of system evacuation is with the use of a: a. Kelvinometer b. Micrometer c. Thermistor vacuum gauge d. Mercury (Hg) vacuum gauge

c. Thermistor vacuum gauge

Very low low-side pressure may be caused by a _________screen in the metering device _________.

clogged, inlet

A ______ type of leak warrants the use of a dye trace solution.

cold

_________ or__________ refrigerant can cause system and equipment damage and present _________ problems if you are not aware of its presence.

cross-contaminated, contaminated, diagnostic

During a system performance test, the low-side gauge is reading a vacuum. Which of the following is the most likely cause? a. An overcharged system b. Incorrectly connecting the gauge hoses to the wrong service ports c. An expansion valve stuck open d. A restricted expansion valve

d. A restricted expansion valve

An R-134a expansion valve system that is properly charged has the following gauge readings, high-side 165 psig and low-side 40 psig and the ambient air temperature is 85°F. Which of the following is the most likely cause? a. A restricted receiver drier b. A restricted condenser c. An out of adjustment temperature blend door d. A stuck open expansion valve

d. A stuck open expansion valve

Refrigerant system air contamination may be caused by: a. Refrigerant system low-side leak. b. Improper system evacuation or insufficient evacuation time. c. Weak evacuation pump. d. All of the above

d. All of the above

An R-134a thermal expansion valve system contains the proper refrigerant charge. During a system performance test, the low-side gauge reading is 40 psig and the high-side gauge reading is 140 psig with an ambient air temperature of 87°F (30.55°C). Which of the following is the most likely cause of these results? a. An overcharged system b. A restricted evaporator c. A restricted condenser d. An expansion valve stuck open

d. An expansion valve stuck open

A manifold and gauge set is attached to an operating air conditioner. The low-side gauge reading is too high and the high-side reading is too low. What could be the problem? a. Refrigerant overcharge b. Insufficient refrigerant c. Expansion valve stuck open d. Defective compressor

d. Defective compressor

To address the issue of small capacity refrigerant systems, the EPA adopted a new SAE standard effective December 2007, covering the accuracy level of future refrigerant recovery, recycling, and recharging equipment. The SAE number for this new standard is: a. J1850 b. 2197 c. J2210 d. J2788

d. J2788

Technician A says that an overcharged system will result in lower than normal low-side pressures. Technician B says that an overcharged system will result in a slight increase in cooling capacity, but only under low load conditions. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

d. Neither A nor B

Technician A says that if the orifice tube is missing, the low-side pressure will be low. Technician B says that if the orifice tube is plugged with debris, low-side pressure will be high. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

d. Neither A nor B

Technician A says that one need not evacuate the system if the "sweep and purge" method is used. Technician B says that one need not evacuate the system if it has been "opened" for less than 5 minutes. Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

d. Neither A nor B

Technician A says that the minimum flow test on a TXV is made by wrapping the remote bulb in a warm rag. Technician B says that a maximum flow test may be made on a TXV by immersing the remote bulb in ice water (H2O).Who is correct? a. A only b. B only c. Both A and B d. Neither A nor B

d. Neither A nor B

Moisture removal from a refrigerant system is being discussed. The length of system evacuation time required depends on all of the major factors listed below except: a. The amount of moisture in the system. b. The ambient temperature. c. The efficiency of the vacuum pump. d. The amount of oil in the system.

d. The amount of oil in the system.

All of the following statements about injecting a dye solution into the air-conditioning system are true, except: a. Dye is approved for automotive air-conditioning system use. b. Dye is available in either yellow or red. c. A few days after injection, the dye will be visible at the point of the leak. d. The dye affects the overall performance of the system.

d. The dye affects the overall performance of the system.

An R-134a system has both excessively high low-side and high-side system pressures. Which of the following is the most likely cause? a. An air dust delivery system problem b. The refrigerant system is undercharged c. A restriction in the evaporator core d. The refrigerant system is overcharged

d. The refrigerant system is overcharged

During initial system evaluation an unknown refrigerant is identified. Which of the following should a technician do? a. Treat it like R-134a and recover and recycle it. b. Treat it like R-1234yf and recover and recycle it. c. Purge it into the atmosphere. d. Treat it as a contaminated refrigerant.

d. Treat it as a contaminated refrigerant.

Most restrictions are caused by _________, __________ , or_________.

foreign matter, dirt, corrosion

A __________ acid is formed by the chemical combination of refrigerant and moisture.

hydrochloric

_________on the evaporator coil__________ the flow of air through it, resulting in poor or _________cooling.

ice (frost), restricts (stops), no

A high low-side pressure is an indication that the thermostatic expansion valve (TXV) _______restricting the flow of __________.

is not, refrigerant

If a low-side restriction occurs, the low-side gauge reading will be__________ or even a __________.

low, vacuum

The_________ and _________ is an important tool for air conditioning service.

manifold, gauge set

__________ is the primary cause of corrosion in the air-conditioning system.

moisture

Air in the refrigerant system is considered a __________ because at no time are refrigerant system pressures great enough or temperatures low enough to cause air to condense into a liquid.

non-condensable gas

An air-conditioning system __________ is an initial test that determines whether the refrigerant system is operating as designed.

performance test

By checking both _________ and __________, you can gain information above and beyond what your pressure gauges are telling you.

subcooling, superheat

When evacuating a refrigerant system it should be placed under a __________ for a minimum of ____________ minutes to ensure moisture removal from the system.

vacuum, 30

If a refrigerant system is contaminated with moisture, the pressure in the system will swing between a ________to ________on the low-side gauge and between _________to _______ on the high-side gauge.

vacuum, normal, low, normal