Flashcards in AC Deck (40)
The pressure at which the refrigerant changes state from a vapor to liquid
The pressure at which the refrigerant changes state from a liquid to vapor
T/F Superheat always refers to a vapor.
T/F All liquid must be vaporized for superheating to occur
Subcooling always refers to a liquid at a temperature _____ its saturation temperature for a given pressure.
One main function of a compressor
One function of discharge line
Carry high pressure superheated vapor from compressor discharge valve to condenser
Receiver acts as a ____.
T/F Liquid line transfers low pressure subcooled liquid to metering device.
F high pressure
Meters liquid refrigerant from liquid line to evaporator
The metering device is a restriction that separates high pressure side from _____ _____ _____ in refrigerant system.
Low pressure side
The evaporator, like the condenser, acts as a _____ _____.
_____ transports low pressure superheated vapor from evaporator to compressor.
4 stages of refrigeration cycle
Superheat on the systems low side can be divided into 2 types:
Total (compressor) superheat
What controls evaporator superheat?
Low evaporator loads can be caused by 4 things:
Iced up or dirty coil
Defrost circuit malfunction causing coil icing
End of refrigeration cycle
Low refrigerant charge
When liquid refrigerant enters the compressor crankcase while compressor is running is called _____.
Name 2 things could cause slugging to occur?
3 metering devices
Thermostatic expansion valve (TXV)
Automatic expansion valve (AXV)
If the diameter is too small _____,
the evaporator will be starved.
If a capillary tube is over/under charged, it will backup the excess liquid in the condenser causing high/low head pressure.
It is extremely important to install a filter drier before the capillary tube to catch any _____ _____.
3 main functions of TXV
Provide constant amount of evaporator superheat
Keep evaporator full of refrigerant
Prevents flood back of refrigerant to compressor
Air may enter refrigeration system because of what 3 things?
Tube, gasket or flange leaks
Poor charging procedures
Poor recovery or recycling procedures
2 types of leak detection
Ultraviolet (UV) Fluorescent
What 2 things are detrimental to a refrigeration system?
New and replacement compressors come shipped with dry nitrogen that needs to be removed and _____ prior to use.