Low airflow over a residential split system air conditioning evaporator can cause
A: Liquid flood-back to the compressor
B: A decrease in
... [Show More] compression ratio
C: An increase in suction line superheat
D: Oil logging in the evaporator - CORRECT ANSWER A: Liquid flood-back to the compressor
Which of the following is the correct sequence of work?
A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the system.
B: Recover refrigerant, evacuate the system, replace filter core, recharge the system.
C: Attach gauge manifold, evacuate the system, replace filter core, recover refrigerant, recharge the system.
D: Attach gauge manifold, recharge the system, evacuate the system, replace filter core. - CORRECT ANSWER A: Attach gauge manifold, recover refrigerant, replace filter core, evacuate the system, recharge the system.
As the pressure on a liquid is increased, the vaporization temperature of the liquid
A: Decreases
B: Increases
C: Remains unchanged
D: Varies - CORRECT ANSWER B: Increases
An oil separator must be mounted
A: Level
B: Below the compressor crankcase
C: Above the compressor crankcase
D: In the suction line - CORRECT ANSWER A: Level
Which of the following metering devices controls evaporator pressure?
A: Thermostatic expansion valve
B: Fixed orifice
C: Low side float
D: None of these - CORRECT ANSWER D: None of these
An automatic expansion valve controls evaporator pressure.
The purpose of the external equalizer on a thermostatic expansion valve is
A: To equalize evaporator pressure drop with respect to the TEV
B: To equalize the evaporator pressure drop
C: To help prevent liquid floodback
D: To allow the high side pressure to equalize to the low side when the compressor cycles off - CORRECT ANSWER A: To equalize evaporator pressure drop with respect to the TEV
The higher the MERV rating of a filter-drier, the
A: More efficient the drier at absorbing moisture
B: Less efficient the drier at absorbing moisture
C: Smaller the particles the filter can entrap
D: MERV does not apply to filter-driers - CORRECT ANSWER D: MERV does not apply to filter-driers
Minimum Efficiency Reporting Value - MERV ratings are used to rate the ability of an air conditioning filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. Higher MERV ratings mean fewer dust particles and other airborne contaminants pass through the filter. Filters with a merv rating of 9 to 12 are used in commercial and industrial applications and will stop particles in the 1 to 3 micron range. These filters are a great choice for home owners who want the best dust control possible. When using filters with Merv 9 ratings and above it is important to clean or replace them when recommended by the manufacturer because they will have a negative effect on air flow when they become dirty. This can lead to performance problems and decreased operating efficiency. The most efficient filters have merv ratings of 13 to 16 and will stop particles as small as .3 microns. These filters are used in hospitals and other super clean environments.
Zeolite is used with
A: Refrigerant filter-driers
B: HEPA filters
C: Pipe threads
D: Solder - CORRECT ANSWER A: Refrigerant filter-driers
Vacuum pressures are measured in
A: Microns
B: Millimeters of mercury
C: Inches of mercury
D: All of the above - CORRECT ANSWER D: All of the above
The number 25,400 relates to
A: Microns/inch
B: Btu/ton
C: Cfm/hp
D: Cfm/ton - CORRECT ANSWER A: Microns/inch
The general rule of thumb for airflow is
A: 400 cfm/ton
B: 400 cfm/hp
C: 6 cfm/sq
D: 144 cfm/cu - CORRECT ANSWER A: 400 cfm/ton
A double suction riser is used to
A: Help improve refrigerant return
B: Allow the compressor to pump at a greater capacity
C: Decrease suction line resistance
D: Improve oil return as system capacity changes - CORRECT ANSWER D: Improve oil return as system capacity changes
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 air residential split system air conditioning unit?
A: Low on refrigerant charge
B: Low on evaporator airflow
C: Refrigerant overcharge
D: There is probably nothing wrong with the system - CORRECT ANSWER B: Low on evaporator airflow
The normal compression ratio for a typical comfort air conditioning application should be in the range of
A: 1 to 2
B: 1.5 to 2.25
C: 2 to 3 [Show Less]