HVAC: EPA 608 CERTIFICATION EXAM 2025
Are there drop-in replacements for R-12 systems? Why or why not? - ✅✅✅CORRECT -No because
the new refrigerants are incompatible with the oils and lubricants used in R-12 systems.
What type of oil is used in R-134a and what oils will it mix with? - ✅✅✅CORRECT -Ester based oils
and they do not mix with other oils
What type of lubricant is used with HCFCs? - ✅✅✅CORRECT -Alkylbenzene lubricant
What is difference b/w ternary blend a azeotropic blend? - ✅✅✅CORRECT -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? - ✅✅✅CORRECT -It absorbs (takes on) moisture
What is temperature glide and what type of blend won't have it? - ✅✅✅CORRECT -Temp. blend is
the difference between the dew point and the bubble point
Dew Point - ✅✅✅CORRECT -Occurs when saturation temp in evaporator causes refrigerant to
change from liquid to vapor
Bubble Point - ✅✅✅CORRECT -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? - ✅✅✅CORRECT -No
because different refrigerants in blend have different vapor pressures, causing them to leak at uneven
rates
Refrigeration Process - ✅✅✅CORRECT -transfer of heat from one place to another
, Evaporator - ✅✅✅CORRECT -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 - ✅✅✅CORRECT -Takes low pressure, low temp vapor and changes it to a high-temp,
high-pressure, superheated vapor and delivers it to the condenser
Condenser - ✅✅✅CORRECT -Rejects heat from system and changes refrigerant from high-temp,
high-pressure vapor into high-pressure, high-temp liquid
Metering Device - ✅✅✅CORRECT -reduces pressure of refrigerant and changes the high-pressure,
high-temp liquid into low pressure, low temp liquid.
Compound Gauge - ✅✅✅CORRECT -Typically blue and measures low pressure (psig) and vacuum
(inHg).
High Pressure Gauge - ✅✅✅CORRECT -Red and measures high side (discharge) pressure. 0 to 500 psi
What does a compressor compress? - ✅✅✅CORRECT -Vapor
Why will refrigerant migrate to the crankcase in a compressor? - ✅✅✅CORRECT -Because of the
vapor pressure difference between refrigerant and oil
What color is the high pressure gauge? - ✅✅✅CORRECT -Red
What color is the low pressure gauge? - ✅✅✅CORRECT -Blue
What needs to happen if oil has been contaminated by burnout? - ✅✅✅CORRECT -Triple evacuate
system, install permanent filter-drier, conduct deep vacuum before recharging
What are three Rs of refrigeration? - ✅✅✅CORRECT -Recover, recycle, reclaim
Are there drop-in replacements for R-12 systems? Why or why not? - ✅✅✅CORRECT -No because
the new refrigerants are incompatible with the oils and lubricants used in R-12 systems.
What type of oil is used in R-134a and what oils will it mix with? - ✅✅✅CORRECT -Ester based oils
and they do not mix with other oils
What type of lubricant is used with HCFCs? - ✅✅✅CORRECT -Alkylbenzene lubricant
What is difference b/w ternary blend a azeotropic blend? - ✅✅✅CORRECT -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? - ✅✅✅CORRECT -It absorbs (takes on) moisture
What is temperature glide and what type of blend won't have it? - ✅✅✅CORRECT -Temp. blend is
the difference between the dew point and the bubble point
Dew Point - ✅✅✅CORRECT -Occurs when saturation temp in evaporator causes refrigerant to
change from liquid to vapor
Bubble Point - ✅✅✅CORRECT -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? - ✅✅✅CORRECT -No
because different refrigerants in blend have different vapor pressures, causing them to leak at uneven
rates
Refrigeration Process - ✅✅✅CORRECT -transfer of heat from one place to another
, Evaporator - ✅✅✅CORRECT -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 - ✅✅✅CORRECT -Takes low pressure, low temp vapor and changes it to a high-temp,
high-pressure, superheated vapor and delivers it to the condenser
Condenser - ✅✅✅CORRECT -Rejects heat from system and changes refrigerant from high-temp,
high-pressure vapor into high-pressure, high-temp liquid
Metering Device - ✅✅✅CORRECT -reduces pressure of refrigerant and changes the high-pressure,
high-temp liquid into low pressure, low temp liquid.
Compound Gauge - ✅✅✅CORRECT -Typically blue and measures low pressure (psig) and vacuum
(inHg).
High Pressure Gauge - ✅✅✅CORRECT -Red and measures high side (discharge) pressure. 0 to 500 psi
What does a compressor compress? - ✅✅✅CORRECT -Vapor
Why will refrigerant migrate to the crankcase in a compressor? - ✅✅✅CORRECT -Because of the
vapor pressure difference between refrigerant and oil
What color is the high pressure gauge? - ✅✅✅CORRECT -Red
What color is the low pressure gauge? - ✅✅✅CORRECT -Blue
What needs to happen if oil has been contaminated by burnout? - ✅✅✅CORRECT -Triple evacuate
system, install permanent filter-drier, conduct deep vacuum before recharging
What are three Rs of refrigeration? - ✅✅✅CORRECT -Recover, recycle, reclaim
