UNIT 15 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
15-1) What happens to the refrigerant as it passes through the metering device?
15-2) Explain the difference between a fixed metering device and a modulating
metering device.
15-3) What are the two types of fixed metering devices?
15-4) Explain how an air conditioner with a fixed metering device reacts to changes
in outdoor temperature?
15-5) Explain how an air conditioner with a fixed metering device reacts to changes
in indoor temperature.
15-6) List the advantages of the capillary tube.
15-7) What advantages are there to orifice type metering devices?
15-8) List types of modulating metering devices?
15-9) What is the most common application of the high-side float?
15-10) What is the difference between the low side float and the high side float?
15-11) Explain the basic operation of the automatic expansion valve.
15-12) Why is the automatic expansion valve not suited for systems with varying
loads?
15-13) Which way would the adjustment on top of an automatic expansion valve be
turned to increase the evaporator pressure?
15-14) What does a thermostatic expansion valve try to regulate and keep stable?
15-15) What is the difference between internally and externally equalized
thermostatic expansion valves?
15-16) How does a TEV with MOP work?
15-17) What is the difference between a traditional TEV and a balanced port TEV?
15-18) What is the difference between a traditional liquid charged TEV bulb and a
liquid cross-charged TEV bulb?
15-19) What is the purpose of a liquid distributor?
15-20) The electronic expansion valve is activated by a(n).
15-21) How do pulse modulated valves control flow?
15-22) How do electronically controlled step motor valves work?
15-23) An R-22 TEV is set for 12°F superheat. The system is operating with a
suction pressure of 76 psig and a suction line temperature at the bulb of 50°F.
What is the actual operating superheat?
15-24) Which way would the adjusting stem on an expansion valve be turned to
increase the superheat?
15-25) Which way would the adjusting stem on an expansion valve be turned to
decrease superheat?
15-26) What types of problems could cause a TEV system to operate at too high a
superheat?
15-27) Why must technicians be careful when brazing lines to evaporator coils that
have thermostatic expansion valves?
15-28) How can a capillary tube that is restricted with debris be differentiated from a
capillary tube that is restricted with ice?
15-29) What is a bi-flow expansion valve?
15-30) An R-134a TEV is set for 8°F. Thesystem is operating with a suction
pressure of 22 psig and a suction line temperature at the bulb of 50°F. What is
the actual operating superheat?
15-31) What system operating characteristics would you expect from a system that
has a TEV with a dead power element?
15-32) What system operating characteristics would you expect from a system that
has a TEV with a loose sensing bulb?
15-33) What system operating characteristics would you expect from a system that
has a restricted-orifice-type-metering device?
15-34) What system operating characteristics would you expect from a system that
has an oversized-orifice-type-metering device?