HVAC/R FINAL STUDY SCRIPT 2026
COMPLETE QUESTIONS AND SOLUTIONS
●● What type of oil is used in R-134a and what oils will it mix with?
Answer: Ester based oils and they do not mix with other oils
●● What type of lubricant is used with HCFCs? Answer: Alkylbenzene
lubricant
●● What is difference b/w ternary blend a azeotropic blend? Answer:
Ternary blends are three-part mixtures whereas azeotropic blends are
blends of two or more compounds that act like a single compound.
●● What is the trait of a hygroscopic lubricant? Answer: It absorbs
(takes on) moisture
●● What is temperature glide and what type of blend won't have it?
Answer: Temp. blend is the difference between the dew point and the
bubble point
●● Dew Point Answer: Occurs when saturation temp in evaporator
causes refrigerant to change from liquid to vapor
,●● Bubble Point Answer: Occurs when saturation temp in condenser
changes refrigerant from vapor to liquid
●● Will the gases in a ternary blend leak at the same rate? Why or why
not? Answer: No because different refrigerants in blend have different
vapor pressures, causing them to leak at uneven rates
●● Refrigeration Process Answer: transfer of heat from one place to
another
●● Evaporator Answer: Absorbs heat into system from space to be
cooled. Absorption of heat causes refrigerant to boil. Upon leaving,
refrigerant changed to low pressure, low temperature vapor
●● Compressor Answer: Takes low pressure, low temp vapor and
changes it to a high-temp, high-pressure, superheated vapor and delivers
it to the condenser
●● Condenser Answer: Rejects heat from system and changes
refrigerant from high-temp, high-pressure vapor into high-pressure,
high-temp liquid
●● Metering Device Answer: reduces pressure of refrigerant and
changes the high-pressure, high-temp liquid into low pressure, low temp
liquid.
, ●● Compound Gauge Answer: Typically blue and measures low
pressure (psig) and vacuum (inHg).
●● High Pressure Gauge Answer: Red and measures high side
(discharge) pressure. 0 to 500 psi
●● What does a compressor compress? Answer: Vapor
●● Why will refrigerant migrate to the crankcase in a compressor?
Answer: Because of the vapor pressure difference between refrigerant
and oil
●● What color is the high pressure gauge? Answer: Red
●● What color is the low pressure gauge? Answer: Blue
●● What needs to happen if oil has been contaminated by burnout?
Answer: Triple evacuate system, install permanent filter-drier, conduct
deep vacuum before recharging
●● What are three Rs of refrigeration? Answer: Recover, recycle,
reclaim
COMPLETE QUESTIONS AND SOLUTIONS
●● What type of oil is used in R-134a and what oils will it mix with?
Answer: Ester based oils and they do not mix with other oils
●● What type of lubricant is used with HCFCs? Answer: Alkylbenzene
lubricant
●● What is difference b/w ternary blend a azeotropic blend? Answer:
Ternary blends are three-part mixtures whereas azeotropic blends are
blends of two or more compounds that act like a single compound.
●● What is the trait of a hygroscopic lubricant? Answer: It absorbs
(takes on) moisture
●● What is temperature glide and what type of blend won't have it?
Answer: Temp. blend is the difference between the dew point and the
bubble point
●● Dew Point Answer: Occurs when saturation temp in evaporator
causes refrigerant to change from liquid to vapor
,●● Bubble Point Answer: Occurs when saturation temp in condenser
changes refrigerant from vapor to liquid
●● Will the gases in a ternary blend leak at the same rate? Why or why
not? Answer: No because different refrigerants in blend have different
vapor pressures, causing them to leak at uneven rates
●● Refrigeration Process Answer: transfer of heat from one place to
another
●● Evaporator Answer: Absorbs heat into system from space to be
cooled. Absorption of heat causes refrigerant to boil. Upon leaving,
refrigerant changed to low pressure, low temperature vapor
●● Compressor Answer: Takes low pressure, low temp vapor and
changes it to a high-temp, high-pressure, superheated vapor and delivers
it to the condenser
●● Condenser Answer: Rejects heat from system and changes
refrigerant from high-temp, high-pressure vapor into high-pressure,
high-temp liquid
●● Metering Device Answer: reduces pressure of refrigerant and
changes the high-pressure, high-temp liquid into low pressure, low temp
liquid.
, ●● Compound Gauge Answer: Typically blue and measures low
pressure (psig) and vacuum (inHg).
●● High Pressure Gauge Answer: Red and measures high side
(discharge) pressure. 0 to 500 psi
●● What does a compressor compress? Answer: Vapor
●● Why will refrigerant migrate to the crankcase in a compressor?
Answer: Because of the vapor pressure difference between refrigerant
and oil
●● What color is the high pressure gauge? Answer: Red
●● What color is the low pressure gauge? Answer: Blue
●● What needs to happen if oil has been contaminated by burnout?
Answer: Triple evacuate system, install permanent filter-drier, conduct
deep vacuum before recharging
●● What are three Rs of refrigeration? Answer: Recover, recycle,
reclaim
