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UNIT 68 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
68-1) What is indicated by a higher than normal temperature rise across the indoor
coil in the heating cycle?
68-2) How often should throwaway filters be checked?
68-3) Why should automotive oil never be used to lubricate blower motors?
68-4) What are the three major differences between an air-conditioning
and a heat pump system?
68-5) When changing a reversing valve, in what position should the main piston and
also the pilot valve sit?
68-6) Why must the pilot valve be positioned as described in question 5?
68-7) When installing a new valve, it should be protected from getting too hot. What
is the maximum temperature the valve body will tolerate?
68-8) What is the primary refrigeration problem in a heat pump system?
68-9) List four common problems with check valves on a heat pump system.
68-10) What are the indications a check valve has stuck closed on an outside coil?
68-11) Name the four most predominant defrost systems.
68-12) A temperature-differential defrost system will not go into defrost. This is the
most common complaint on this control. Describe the correct solution to this
problem.
68-13) A pressure-time-temperature defrost system goes into defrost with very little
frost on the bottom of the coil. Describe the major cause of and solution to this
problem.
68-14) If the unit does not run, what is the first thing to check?
68-15) Basically, the service problems with heat pumps fall into three main
categories. What are they?
68-16) Why might customers complain about their heat pump systems being cold and
drafty? The supply air temperature is lower than the air of warm air furnaces.
68-17) If the hot gas sensor located in the compressor discharge line shuts down the
compressor, this may indicate what?
68-18) If the high-pressure switch located in the compressor discharge line shuts
down the compressor, this may indicate what?
68-19) How should the accumulator for a heat pump system be sized, and why?
68-20) Why is it not recommended to energize the solenoid coil when it is not
installed on the reversing valve?
