Heat can neither be _____ or _______.
created, destroyed
Heat moves from _____ to _____.
hot, cold
Boiling point of a substance is proportionall related to the ______ it is under. The higher the pressure, the higher the ____ _____.
pressure, boiling point
suction pressure is also called low pressure and______ ____
back pressure.
5 compressors used in hvac are
1- scroll 2- reciprocating 3- screw 4- rotary 5- centrifugal
compressor with fewest moving parts made in the late 1980s. Compresses vapor volume into smaller and smaller area.
scroll: orbiting scroll moves and fixed scroll doesnt move.
which compressor are not designed to handle liquid refrigerant.
scroll and recipricating
In a single phase motor an overload is either internal between the _____ and common windings. overload can also be on the same motor externally mounted.
start, run
Never take resistance reading directly on compressor terminals. Always use _____ ______ instead. Safety precaution.
wire leads.
If reading an open circuit between c and windings always _____, connections are ____and _____ hasnt burned off. Check continuity of the wires as well
visual inspection of terminals, tight, common wire
Causes of an open internal overload are
- low refrigerant/ ineffient cooling of the compressor.
- excessive refrigerant charge/ too much load/ amps/heat.
- non condensables/ air in the superheated gas in suction line and discharge line causing no refrigerant cooling of compressor.
- excessive air flow can cuase too much superheat, in efficient cooling of compressor.
- low/no airflow at condenser/ no subcooled refrigerant at metering device/ excessive super heat, no cooling of compressor.
- failing/failed capacitor.
-
line wire must be sized by guage and length to handle ______
minimum circuit ampacity
Make sure the _______ panel is the proper sized to handle all _____ within the structure.
breaker, loads
If there are complaints of dimming lights check all wire _______ are clean and _____ between the breaker to the compressor terminals.
connections, tight.
