Auto 135

During a retrofit, the replacement R-134a charge should be ________ than the specified R-12 charge.

10% minus 4 oz. less

Technician A says AC system lines and hoses that are cold have lower refrigerant pressure than warmer lines and hoses. Technician B says frost on a system component usually indicates a refrigerant leak in that area. Which technician is correct? Group of answer choices

A

Which of the following is NOT a component of an automatic temperature control system?

A. All of these are components of a semi-automatic B. temperature control C. Temperature sensors D. Control head E. Electrically or vacuum operated actuators ANSWER: A

The ambient temp. sensor is____________?

A. In front the radiator B. In the air intake duct C. Both ANSWER: C

When replacing a compressor clutch, what adjustment is needed?

Air gap

Technician A says electronic leak detectors work better when there is more air current and the sensor is moved rapidly. Technician B says that UV leak dye can be added to the A/C system and checked with an ultraviolet light. Which technician is correct?

B

Technician A says that the system should be put under a vacuum so that all the old oil is removed. Technician B says that system evacuation (vacuuming) is done to remove moisture from the system. Which technician is correct?

B only

Technician A says that vacuum is usually measured in psi. Technician B says vacuum is usually measured in inches of mercury (Hg). Who is correct?

B only

Technician A says to charge the system with refrigerant until the condenser temperature is equal to the ambient temperature plus 100 deg. F. Technician B says to charge the system with a manufacturer specified weight of refrigerant. Which technician is correct? Group of answer choices

B only

Two technicians are discussing how to remove refrigerant from a system. Technician A says that you can vent it into the atmosphere as long as it has moisture in it. Technician B says that all refrigerant must be captured. Who is correct?

B only

Which of these is an example of a three-position actuator?

Bi-level air door

The door used to control interior temperature is called BLANK door

Blend door

Technician A says that with a properly operating air-conditioning system, the inlet to the compressor should be cold and the outlet from the compressor hot. Technician B says that the condenser should be hot and the evaporator cold. Which technician is correct?

Both

Technician A checks ambient temperature as part of an AC performance test. Technician B says that if the AC compressor has not been operating, the high side and low side refrigerant pressure should be equal. Who is correct?

Both A and B

Technician A says a thermostat which opens too soon can cause poor heater operation. Technician B says low coolant level can cause poor heater operation. Which technician is correct?

Both A and B

Technician A says that oily residue on hoses, components, or fittings indicates an area where refrigerant may be leaking. Technician B says that clogged evaporator fins may cause inefficient air conditioning operation at all blower speeds. Which technician is correct?

Both A and B

Technician A states that the evaporator and heater housing can be called a plenum. Tech B states that besides the evaporator and heater core, the housing also has the blower motor and control doors. who is correct?

Both techs

Which sensor informs the control module of the temperature at the end of the air ducts where it blows into the cabin.

Discharge air temp. sensor (DAT)

In most HVAC systems, outside air is first directed to the BLANK and flows then to the BLANK

Evaporator, heater core

What service procedure should be performed before recovering refrigerant from an A/C system?

Identify the type of refrigerant AND Pre-condition the system

What is the term used to describe the "extra" heat needed to transform a substance from one state to another?

Latent heat

During the Zoom session on 4/29/20, the 2003 Audi A4 wagon had a fault for which flap motor?

Left Temp. Flap motor (V158)

If both the low side and the high side show low readings, what might be the problem?

Low refrigerant charge

The HVAC control head is connected to various components by:

Mechanical cable, electrical connections and vacuum connections

The BLANK door is used to select air discharge location such as floor, vent or defrost.

Mode

Tech A states that dual-zone systems are mainly there to blend the evaporator and heater core airflow and direct it to the driver and passenger equally. Tech B states that the blend door is responsible for directing airflow down to the inside floor. who is correct?

Neither

Technician A says that an AC system with an orifice tube uses a receiver dryer to filter the refrigerant. Technician B says that if water is draining from the evaporator housing, the compressor needs to be replaced.

Neither Techs

R-1234yf refrigerant is mildly flammable. because of this, if the evaporator is damaged, it must replaced with a BLANK evaporator

New

What type of sensor senses sunlight?

Photo diode

Which component is used as a feedback circuit?

Potentiometer

What type of service valves are used with R-134a?

Quick disconnect valves

What mode blocks the air coming in from outside of the vehicle and uses the air inside of the vehicle instead?

Re circulation

where in the air conditioning system is the refrigerant a high pressure liquid

Receiver dryer, Expansion valve, condenser

If a resistor-type blower motor only blows when set to "4" or MAX, the most likely fault is?

Resistor

What type of doors are used in a HVAC system?

Rolling door, rotary door, and swinging door

Tech A states that electronic controls often use a signal voltage between 0 and 5 volts to control actuator motors. Tech B states that all actuators with self calibrate after replacement. which tech is correct?

Tech A

Technician A says that a calorie is the heat needed to raise the temperature of one gram of water to one degree Celsius. Technician B says that heat and temperature are both measured in degrees. Which technician is correct?

Tech A

Technician A says that the refrigerant capacities can be located under the hood of the vehicle. Technician B says that if a system is not cooling enough, one should give it just a little extra charge. Who is correct?

Tech A

Technician A says that when the defrost setting is on the recirculation door closes the outside air flow and recirculates the inside air. Technician B states that for the defrost setting, the airflow is set to the windshield. who is correct?

Tech A

Tech A states that if the variable resistor for the blower motor is defective, only low speed is available. Tech B states that some blower motors are controlled by the body control module. which tech is correct?

Tech B

Technician A says that ALL cabin filters are accessible behind the glove compartment. Technician B says that some cabin filters are accessible from under the hood. Which technician is correct?

Tech B

Technician A says that an HFC 134a system uses a mineral oil. Technician B says that failure to use the correct oil can cause system damage. which technician is correct?

Tech B

What is the purpose of evacuating the AC system? Group of answer choices

To eliminate any moisture inside the system

A micron gauge is a better indicator of vacuum than a gauge calibrated in in. Hg

True

If the performance test shows between 34° F and 45° F at the center vent, the AC is working normally.

True

A dual-zone climate control system allows the driver and passenger to set individual temperatures. What components are needed in the most basic dual-zone system?

Two air mix doors

What type of compressor system control pressure?

Variable displacement, EPR valve, cycling clutch orifice tube system

A thermal expansion valve has a BLANK orifice, whereas an orifice tube uses a BLANK orifice to control refrigerant flow.

Variable, fixed

The outlet line from the evaporator should be ________.

cool

What is the primary purpose of "Afterblow" as described in the text?

dry the evaporator

Hot coolant is circulated through the heater core to warm the vehicle interior. Cool refrigerant absorbs heat in the vehicle interior by passing through the ______?

evaporator

where in the air conditioning system is the refrigerant a low pressure?

evaporator outlet

When replacing the Evaporator, especially if the customer was charged to remove the dash board, one should recommend the ____________.

heater core

Compressing a vapor

increases the pressure and increases the temperature

O-rings are usually made from ________.

neoprene

A clogged ________ tube can cause a lack of cooling. Group of answer choices

orifice tube

The cabin air filter is also called

pollen filter and particulate

Which of the following must always be replaced when a retrofit is performed?

refrigerant oil

Most rigid refrigerant lines are made of BLANK

rubber and fabric, aluminum

Electric and some hybrid vehicles use an A/C compressor that is driven by ________.

the high voltage battery

An air conditioning performance check requires a ________. `

thermometer and a manifold gauge set

A defective thermostat can cause the engine to operate ________.

too hot and too cold