Question 1

An APAD CM-813 module does not receive input information from:

Accepted Answer

The APAD CM-813 module does not receive input information from the ECM fan relay, as it typically receives inputs from pressure switches and the cab thermostat.

Question 2

An APAD CM-813 module does not deliver output signals to:

Accepted Answer

The APAD CM-813 module typically does not deliver output signals to the evaporator fan, as it is more likely to control components like the compressor clutch, fan actuator, and diagnostic LEDs.

Question 3

What is the possible cause for a dash message "No RPM message"?

Accepted Answer

The dash message "No RPM message" would typically indicate that the engine RPM's are not reaching a level high enough for the vehicle's computer to detect them. Since this message is indicating a lack of RPM signal, it's likely that the engine is spinning too slowly to register. Out of the choices given, an engine RPM of less than 300 would be the lowest and thus most likely to trigger this message.

Question 4

Which of the following could cause low pressure fault?

Accepted Answer

All of the listed factors could cause a low pressure fault. Cold ambient temperatures can cause low pressure by decreasing the pressure inside the refrigeration system. Loss of refrigerant can also cause low pressure because there is less refrigerant available to create pressure. Blockage in the evaporator can cause low pressure because it restricts the flow of refrigerant, which reduces pressure in the system.

Question 5

APAD or ACPU systems are designed to reduce maintenance costs associated with the HVAC system by:

Accepted Answer

APAD or ACPU systems primarily focus on controlling the compressor operation to optimize the HVAC system's efficiency and reduce maintenance costs.

Question 6

How does the APAD and ACPU system lubricate the compressor and components all year long?

Accepted Answer

The APAD (Ambient Pressure And Temperature Dependent) and ACPU (Air Conditioning Pressure Unit) systems engage the compressor for a short period after the vehicle starts. This action ensures that the oil, which lubricates the compressor and other components, circulates throughout the system, maintaining lubrication even when the air conditioning is not in use for extended periods, such as during colder months. This process helps prevent the compressor and other components from drying out and becoming damaged.

Question 7

An air conditioning system battery voltage low fault indicates a voltage drop below:

Accepted Answer

A voltage drop below 11 volts in an air conditioning system battery typically indicates a low fault condition. This threshold is set to ensure the system has enough power to operate effectively without causing damage or inefficiency.

Question 8

If you got a dash message "A/C SYST CLUTCH CIR SHORT" which component would you test?

Accepted Answer

The message indicates a short in the clutch circuit, so the component to test would be the clutch coil.

Question 9

Which of the following would NOT cause a low voltage fault?

Accepted Answer

High refrigerant pressure would not cause a low voltage fault, as it is related to the air conditioning system and not the electrical system. Defective charging systems, excessive electrical loads, and discharged or defective batteries can all cause low voltage faults in a vehicle.

Question 10

APAD and ACPU relieves stress on the engine starting system by not allowing the compressor clutch to engage until the engine has been running for:

Accepted Answer

The APAD and ACPU systems are designed to delay the engagement of the compressor clutch for 15 seconds after the engine starts to reduce stress on the engine starting system.

Question 11

Which of the following would NOT cause a high pressure switch open fault?

Accepted Answer

A high pressure switch open fault is typically caused by low refrigerant charge, a faulty switch or a clogged or blocked condenser. Refrigerant overcharge would not cause this fault.

Question 12

A dash message "low air" and the air conditioning compressor not engaging indicates the system air pressure is below:

Accepted Answer

The air conditioning compressor typically requires a minimum system pressure to engage, often around 60 PSI. If the pressure drops below this threshold, it can trigger a "low air" warning and prevent the compressor from engaging to protect the system.

Question 13

Which of the following would NOT cause a high pressure fault?

Accepted Answer

A high pressure fault is caused by an increase in pressure in the refrigeration system. A fan drive failure, condenser blockage, and refrigerant overcharge can all lead to high pressure in the system. However, an evaporator blockage would cause low pressure rather than high pressure.

Question 14

Which of the following could cause a fault code erratic TStat?

Accepted Answer

Any of these issues with the thermostat, A/C ON switch, or wiring connections could potentially cause an erratic TStat fault code.

Question 15

How are blink codes cleared from a CM-813 module?

Accepted Answer

Both cycling the ignition switch and self-clearing are valid methods for clearing blink codes from a CM-813 module. Removing the negative ground cable from the vehicle battery may reset the module, but is not specifically mentioned as a recommended method in this context.

Quiz 11: Apadsacpu Air Conditioning Control Systems Air Conditioning Protection Unit