HVAC Quiz 5

Put the steps of retrofitting in the correct order.

1. Conduct a performance and leak test and analyze the refrigerant in the system. 2. Recover R-12 refrigerant and perform repairs. 3. Install R-134a service ports and high pressure switch, if necessary. 4. Add PAG or POE oil to the A/C system, evacuate, and recharge with R-134a. 5. Verify repair and affix new label.

Match each TXV component to its correct location: 1. 2.

1. diaphragm 2. capillary tube

Match each TXV component to its correct location: 3. 4.

3. sensing bulb 4. equalizing tube

The high pressure relief valve will typically operate at what dangerous level?

440 psi

Match each TXV component to its correct location: 5. 6.

5. inlet screen 6. needle and seat

Match each TXV component to its correct location: 7. 8.

7. pressure spring 8. valve body

The water control valve door closes when the ________________.

A/C turns on

Technician A says that air passing through the evaporator becomes cooler. Technician B says refrigerant that absorbed the heat from the air in the evaporator becomes warmer and turns into a vapor. Which technician is correct?

Both Technicians A and B

Technician A says that if you don't find evidence of a leak at the drain pipe, you should still continue to check for a leak in other areas. Technician B says that if you find a leak in the evaporator, you will need to replace it. Which technician is correct?

Both technicians A and B

Technician A says that the blower motor draws in air to circulate through the ductwork. Technician B says that the operator control panel regulates the amount of air circulating in the vehicle. Which technician is correct?

Both technicians A and B

Technician A says that the mode knob moves the cable core within the cable housing. Technician B says that the movement of the cable core transfers the driver's motion to the temperature, mode, or recirculation door. Which technician is correct?

Both technicians A and B

Technician A says that there are a few heater cores that have plastic tanks. Technician B says that heater cores constructed of copper and brass or aluminum make great heat conductors. Which technician is correct?

Both technicians A and B

Technician A says the auxiliary water pump forces more or less coolant into the heater core based on the operator's desired temperature. Technician B says that auxiliary water pumps are used in some vehicles to heat the passenger compartment for a short time after the engine stops running. Which technician is correct?

Both technicians A and B

Technician A says that when the mode switch is turned to the OFF position, it creates more vacuum. Technician B says that when a car accelerates, the engine manifold vacuum is high. Which technician is correct?

Neither technician A nor B

Which of the following is the only refrigerant approved by the EPA for use in automotive air conditioning systems?

R-134a

Technician A says that if air distribution routes incorrectly, there may be a malfunction with one of the vacuum actuators. Technician B says that when you apply vacuum through either of the actuator ports, a plastic diaphragm will move the actuating rod. Which technician is correct?

Technician A

Technician A says that if you can't remove the cabin air filter, the blower motor, or the blower resistor to access the evaporator core, you need to drill in the HVAC case. Technician B says that you can also coat the evaporator with a chemical coating using the afterblow feature that is available in the HVAC control module. Which technician is correct?

Technician A

Technician A says that once the operator turns on the blower speed switch, the blower begins to pull air into the HVAC system. Technician B says that once air passes through the heater core, it then goes through the evaporator. Which technician is correct?

Technician A

Technician A says that when you suspect a plugged heater core, contaminants in the coolant may be the cause. Technician B says that if you suspect a coolant restriction to the heater core, the inlet hose to the core will be cool, but the outlet hose will be much cooler. Which technician is correct?

Technician A

Technician A says that if you find a rusted or loose hose clamp, or an oily hose, you do not need to replace either part because it is due to general wear and tear. Technician B says if you see a hose in the HVAC system with cracks, fraying areas, or swelling, you should replace it. Which technician is correct?

Technician B

Technician A says that some vehicles use water control valves on the hoses that connect to the heater core and evaporator. Technician B says that in vehicles without water control valves, heat comes into the HVAC system once the engine is hot. Which technician is correct?

Technician B

Technician A says that the single-zone system ductwork allows separate temperature adjustments for the driver and the passenger. Technician B says the single-zone system controls the temperature for the entire vehicle based on operator setting. Which technician is correct?

Technician B

Technician A says that there are three common types of evaporator pressure regulator systems: the pilot absolute pressure valve, suction throttling valve, and ball valve. Technician B says the valve controls evaporator pressure by closing when the pressure in the evaporator gets too low, usually between 29 and 31 psi. Which technician is correct?

Technician B

Technician A says that when retrofitting, you must install a new pressure-relief device that automatically releases refrigerant to the atmosphere. Technician B says that when retrofitting, you need to use unique service fittings to minimize the risk of cross-contamination on either the air conditioning system or the recycle station. Which technician is correct?

Technician B

Technician A says that when you move the mode switch to OFF on the control panel, this makes an electrical contact in the control head of the FIVAC system. Technician B says the vacuum actuators cause the mode doors to move when the driver makes a selection other than OFF on the control panel. Which technician is correct?

Technician B

What function does an evaporator perform?

absorbs and removes heat from the air of the passenger cabin

Match each description to its correct component: controlled by the vacuum programmer

actuators

The H-valve is ____________.

an expansion valve

Fins

are metal surfaces that absorb heat and condense moisture from the ambient air that will be blown into the cabin of the vehicle

What draws in air to circulate through the ductwork?

blower

Circulates air in the passenger cabin

blower motor

What does the intake ductwork direct into the HVAC system?

both outside and recirculated inside air

What is used in the thermostatic de-icing switch to measure evaporator temperature?

capillary tube

The compressor coil is usually switched on or off by a _____.

clutch relay

The vacuum lines to and from the control panel are:

color-coded

Where is the high pressure relief valve located?

compressor

What actuates the water control valve?

control head

The _____ receives inputs on vehicle performance and conditions.

control module

What is the primary function of TXV systems?

control the refrigerant flow

Heat from air transfers across the refrigerant tubes of the evaporator using a principle known as __________.

convection

Match each description to its correct component: where the vacuum programmer is located

dash

Refrigerant filters will need to be replaced due to?

debris from the compressor breakdown

If vacuum is lost to the control panel, air directs to the:

defrost vents

Match each heating system to its correct description: Each side uses separate ductwork and distribution doors.

dual-zone

The external valve uses an _________ line that connects to the evaporator outlet line.

equalizer

Similar to the condenser in that it consists of refrigerant coils mounted on thin cooling fins

evaporator

The H-valve is located across the ____________ inlet and outlet.

evaporator

The internal valve uses an internal equalizer passage to sense the ________ inlet pressure.

evaporator

What is another name for thermostatic de-icing sensor?

fin switch

Laminated Plates

help prevent buildup of contaminants and mold

Refrigerant first enters the H-valve as a ____________.

high pressure liquid

R-134a works similarly to R-12 but operates at a _____________.

higher pressure

Match each description to its correct component: connect to the actuators, which help route vacuum

hoses

Which filter is usually installed as an aftermarket component?

in-line

The TXV is mounted at the _____ to the evaporator.

inlet

The blower motor credit card has a(n) __________ that attaches to a circuit board.

integral connector

A water control valve can have a ___________________.

metal or plastic housing

Match each description to its correct component: move when the vacuum actuator engages

mode doors

The thermostatic de-icing switch is used to turn the cycling clutch __________.

on or off

Acts as a metering device that regulates the flow of liquid refrigerant

orifice tube or TXV

What is another name for high pressure relief valve?

popoff valve

Tube Plates

provide an internal passage for circulating refrigerant and an external passage for incoming air

Match each heating system to its correct description: Driver can typically override the system settings.

rear auxiliary unit

Multipass

refrigerant comes in one side and snakes back and forth within a single tube

The ball valve is a variable restriction used to control ____________.

refrigerant flow

Single Pass

refrigerant flows through multiple tubes from one side to the other

The _____ helps prevent damage to the control module.

relay control circuit

Match each heating system to its correct description: This system has one evaporator core, heater core, control head, and one temperature control switch.

single-zone

Match each description to its correct component: moves a mechanical vacuum switch inside the programmer

solenoid

H-valve has a ____________ .

temperature sensing element

The ________ is used as a protection device.

thermal limiter

What does TXV stand for?

thermostatic expansion valve

Which door system allows air to be distributed through more than one vent?

three-position door system

Match each heating system to its correct description: This system directs air from the front plenum to the rear seat passengers.

tri-zone

The cause of a constant hissing noise from the control vent is a(n):

vacuum leak