week 5 hvac

A common engine thermostat has a temperature rating of:

195 degrees Fahrenheit

When the cooling system is placed under pressure, for each pound per square inch (psi) of cooling system pressure, the boiling point of the coolant is increased by:

3 degrees Fahrenheit

Engine coolant loss could be caused by all of the following except:

A leaking transmission cooler line.

If a thermostat fails in the open position, all of the following will occur, EXCEPT:

A loss of engine coolant.

All of the follow are true about engine thermostats EXCEPT:

A thermostat may be removed from a system if it is running hot.

Reciprocating compressors are being discussed. Technician A says that the suction valve is opened to allow refrigerant vapor to enter due to a differential in pressure above and below the valve. Technician B says the discharge valve is opened to allow refrigerant vapor to leave due to a differential in pressure above and below the valve.

Both A and B

The function of a scroll compressor is being discussed. Technician A says that its function is to create a low pressure condition in the system. Technician B says that its function is to increase the temperature and pressure of refrigerant vapor

Both A and B

The method used to drive a compressor are being discussed: Technician A says that automotive air conditioning compressors have an electromagnetic clutch. Technician B says that a serpentine belt system is often used to drive a compressor clutch.

Both A and B

The following are automotive air conditioning system compressor types, except:

Centrifugal

A technician finds an air conditioning clutch will not engage. Upon initial testing the compressor is receiving both proper power and ground at the compressor clutch electrical connector; in addition the compressor input shaft turns freely by hand. Which of the following is the most likely cause?

Compressor clutch air gap is too large.

An air conditioning compressor clutch failed due to overheating. What is the most likely cause of the failure?

High resistance in the compressor

All of the following statements about engine cooling systems are true EXCEPT:

It is ok for a technician to install a thermostat with a low temperature rating than the original thermostat.

Engine coolant is designed to provide all of the following EXCEPT:

Lower the boiling point of the solution.

After a vehicle has been driven for 10-15 miles, the heater still continues to blow cool air. Which of the following is the most likely cause?

Partially blocked heater core.

Electric motor-driven air conditioning compressors used on hybrid vehicles are based on what compressor design?

Scroll compressor design

The electronic variable displacement compressor is based on what type of compressor design?

Swash plate compressor design

Air in the cooling system can cause all of the following except:

The coolant hoses to burst due to air pressure.

All of the following are the function of the radiator pressure cap except:

To lower the freeze point of the coolant

The compressor pumps refrigerant as a?

Vapor

All of the following statements about variable displacement compressors are true, except?

Variable displacement compressors have a cycling clutch.