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Questions and Answers
Low airflow over a residential split system air conditioning evaporator can cause
Low airflow over a residential split system air conditioning evaporator can cause
- An increase in suction line superheat
- Oil logging in the evaporator
- Liquid flood-back to the compressor (correct)
- A decrease in compression ratio
Which of the following is the correct sequence of work?
Which of the following is the correct sequence of work?
- Attach gauge manifold, evacuate the system, replace filter core, recover refrigerant, recharge the system.
- Attach gauge manifold, recharge the system, evacuate the system, replace filter core.
- Recover refrigerant, evacuate the system, replace filter core, recharge the system.
- Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the system. (correct)
As the pressure on a liquid is increased, the vaporization temperature of the liquid
As the pressure on a liquid is increased, the vaporization temperature of the liquid
- Varies
- Remains unchanged
- Increases (correct)
- Decreases
An oil separator must be mounted
An oil separator must be mounted
Which of the following metering devices controls evaporator pressure?
Which of the following metering devices controls evaporator pressure?
The purpose of the external equalizer on a thermostatic expansion valve is
The purpose of the external equalizer on a thermostatic expansion valve is
The higher the MERV rating of a filter-drier, the
The higher the MERV rating of a filter-drier, the
Zeolite is used with
Zeolite is used with
Vacuum pressures are measured in
Vacuum pressures are measured in
The number 25,400 relates to
The number 25,400 relates to
The general rule of thumb for airflow is
The general rule of thumb for airflow is
A double suction riser is used to
A double suction riser is used to
A service technician measures a return air temperature of 80 degrees and a supply air temperature of 55 degrees. What, if anything, may be wrong with this residential split system air conditioning unit?
A service technician measures a return air temperature of 80 degrees and a supply air temperature of 55 degrees. What, if anything, may be wrong with this residential split system air conditioning unit?
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Study Notes
Low Airflow Issues
- Low airflow over a residential split system air conditioning evaporator can lead to liquid flood-back to the compressor, causing potential damage.
Correct Sequence of Work
- The proper sequence for air conditioning service is: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, and finally recharge the system.
Vaporization Temperature
- Increasing pressure on a liquid raises its vaporization temperature, affecting performance and efficiency in cooling systems.
Oil Separator Installation
- An oil separator must be mounted level to ensure proper operation and oil return to the compressor crankcase.
Metering Devices
- An automatic expansion valve, not the listed metering devices, is responsible for controlling evaporator pressure in air conditioning systems.
Purpose of External Equalizer
- The external equalizer on a thermostatic expansion valve equalizes evaporator pressure drop concerning the TEV to maintain system balance.
MERV Ratings
- MERV ratings do not apply to filter-driers. They measure the efficiency of air filters in removing airborne contaminants, with higher ratings indicating better filtration capabilities.
Zeolite Use
- Zeolite is utilized in refrigerant filter-driers for effective moisture absorption within the cooling system.
Measuring Vacuum Pressures
- Vacuum pressures can be measured in microns, millimeters of mercury, and inches of mercury, providing flexibility in measurement standards.
Microns to Inches Relation
- The number 25,400 relates to microns per inch, an important conversion factor in vacuum measurement.
Airflow Rule of Thumb
- A general guideline for airflow is 400 cubic feet per minute (cfm) per ton of cooling capacity in typical comfort air conditioning applications.
Double Suction Riser Function
- A double suction riser is used to improve oil return as system capacity changes, enhancing overall performance and reliability.
Air Temperature Measurements
- Measuring a return air temperature of 80 degrees and a supply air temperature of 55 degrees may indicate low evaporator airflow, suggesting potential system issues.
Normal Compression Ratio
- The typical compression ratio for comfort air conditioning systems ranges from 1 to 2, indicating acceptable operational parameters.
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