Thanks for stopping by OldSchoolNoe . That's true. Moisture is horrendous; remember that it freezes in the expansion valve. This problem can result in warm air midway through the test drive. - see www.freeasestudyguides.com/ac-frozen-expansion-valve.html - n - Good Luck with the A7!
For question 2, doesn't 135 on the high side seem a bit low? My instinct was telling me the answer was B (low system charge). The only thing causing me to hesitate was the fact that the evaporator temp was reading nice and cold. Either way, much appreciate these practice tests and thank you!
That's a great comment, Justin! It depends. Air conditioning system pressures are affected by temperature. The ambient temperature/pressure chart for 134a refrigerant indicates a 25-35 low-side and 135-155 psi high-side, this is at 65 degrees. The high-side pressure increases to 145-160 psi at 70 degrees. Thanks for the input - Good Luck!
Thanks for the feedback bimmerTEK! I hope this helps. The image of a blend door contains a motor and a variable resistor. Answer A is correct because it's an EXCEPT type question; the image contains a stepper motor with a potentiometer (variable resistor) that provides feedback to the controller about its position. Air conditioning cases contain air doors that control the flow of air through the system. There are at least three diverter doors and one blend door in the basic air conditioning system. Diverter or mode doors are typically either open or closed, while blend doors that mix air to achieve the desired temperature have numerous positions. An air blend door is an example of a door that needs more precise control. Blend doors have stepper motors that have many positions (0 - 255). A five-wire motor contains a potentiometer indicating the blend door's position to the controller. A two-wire motor either opens or closes a door; the outside air recirculation door is an example of a door that is either open or closed.
I had an issue with #5. If there was moisture in the system, the system would perform poorly at various temperatures, not just at the hottest time.
Thanks for stopping by OldSchoolNoe
. That's true. Moisture is horrendous; remember that it freezes in the expansion valve. This problem can result in warm air midway through the test drive. - see www.freeasestudyguides.com/ac-frozen-expansion-valve.html - n - Good Luck with the A7!
In question #4 can we just check the service manual for correct refrigerant recommend?
In question #2 we are to assume the engine is running with the A/C on are we?
For question 2, doesn't 135 on the high side seem a bit low? My instinct was telling me the answer was B (low system charge). The only thing causing me to hesitate was the fact that the evaporator temp was reading nice and cold. Either way, much appreciate these practice tests and thank you!
That's a great comment, Justin! It depends. Air conditioning system pressures are affected by temperature. The ambient temperature/pressure chart for 134a refrigerant indicates a 25-35 low-side and 135-155 psi high-side, this is at 65 degrees. The high-side pressure increases to 145-160 psi at 70 degrees. Thanks for the input - Good Luck!
#8 should be D? Or 2 position you mean on or off only?
Thanks for the feedback bimmerTEK! I hope this helps. The image of a blend door contains a motor and a variable resistor. Answer A is correct because it's an EXCEPT type question; the image contains a stepper motor with a potentiometer (variable resistor) that provides feedback to the controller about its position. Air conditioning cases contain air doors that control the flow of air through the system. There are at least three diverter doors and one blend door in the basic air conditioning system. Diverter or mode doors are typically either open or closed, while blend doors that mix air to achieve the desired temperature have numerous positions. An air blend door is an example of a door that needs more precise control. Blend doors have stepper motors that have many positions (0 - 255). A five-wire motor contains a potentiometer indicating the blend door's position to the controller. A two-wire motor either opens or closes a door; the outside air recirculation door is an example of a door that is either open or closed.
K