3. Open the shutoff valves of the water-cooled
4. Make certain the liquid line solenoid valve(s) is
on automatic control.
5. Open the liquid line shutoff valve.
6. Back-seat the compressor suction and discharge
7. Close the system master electrical disconnect
8. Start the system.
9. After the system has operated for 15 to 20
minutes, check the compressor oil level sight glass, oil
pressure, and the liquid line sight glass. If satisfactory,
readjust the system temperature controller to the proper
Most units used for comfort air conditioning
operate using R-12 or R-22 refrigerants that are not
toxic except when decomposed by a flame. If the
liquefied refrigerant contacts the eyes, the person
suffering the injury must be taken to a doctor at once.
Should the skin come in contact with the liquefied
refrigerant, the skin is to be treated as though it had
been frostbitten or frozen. Refer to NAVEDTRA
13119, Standard First Aid for Treatment of Frostbite.
Do not adjust, clean, lubricate, or service any parts
of equipment that are in motion. Ensure that moving
parts, such as pulleys, belts, or flywheels, are fully
enclosed with proper guards attached.
Before making repairs, open all electric switches
controlling the equipment. Tag and lock the switches
to prevent short circuits or accidental starting of
equipment. When moisture and brine are on the floor,
fatal grounding through the body is possible when
exposed electrical connections can be reached or
touched by personnel.
De-energize electrical lines
before repairing them, and ground all electrical tools.
Q9. What are the two types of self-contained
Q 1 0 . W h o n o r m a l l y o p e r a t e s a w i n d o w
Floor units are often referred to as what type of
What type of unit cools and heats by reversing its
The reversing valve changes the direction of hot
gas from what component to what other
component in the system?
Heat pumps operating below 45°F develop what
problem on the outside coils?
When the capacity of a heat pump matches the
heat loss, it has reached what point?
What are the two most common evaporators
used for water chiller systems?
Dry-expansion evaporators are controlled by
what type of expansion valve?
Why is a tube-within-a-tube condenser popular?
Condensers can be cleaned in what two ways?
Refrigerant coils should be cleaned at least how
MAJOR SYSTEM COMPONENTS AND
Learning Objectives: Recognize and understand
different types of cooling towers, compressors, and
controls. Understand basic maintenance requirements
for cooling towers.
In this section, cooling towers and compressors
which are the two major components of an
air-conditioning system are discussed. In addition, the
major control elements of an air-conditioned system
are also covered.
Cooling towers are classified according to the
method of moving air through the tower as natural
draft, induced draft, or forced draft (figs. 7-19 and
The natural draft cooling tower is designed to cool
water by means of air moving through the tower at the
low velocities prevalent in open spaces during the
summer. Natural draft towers are constructed of
cypress or redwood and have numerous wooden decks
of splash bars installed at regular intervals from the
bottom to the top. Warm water from the condenser is