g. Stand the flushing cylinder upright and flush
the compressor discharge hose. Secure it so the flushing
refrigerant goes into the waste container.
h. Close the dispensing valve of the R-12 or
R-134a can (fully clockwise). If there is any flushing
refrigerant in the cylinder, it may be left there until the
next flushing job. Put the flushing kit and R-12 or
R-134a can in a suitable storage location.
i. Install the new lubricated O rings on the
spring lock coupling male fittings on both the condenser
inlet and the liquid lines. Assemble the couplings.
9. Connect all refrigerant lines. All connections
should be cleaned and new O rings should be used.
Lubricate new O rings with clean refrigerant oil.
10. Connect a charging station or manifold gauge
set and charge the system with 1 pound of R-12 or
R-134a. (Do not evacuate the system until after it has
been leak tested.)
11. Leak test all connections and components with a
flame type of leak detector or an electronic leak
detector. If no leaks are found, go to Step 12. If leaks
are found, service as necessary; check the system and
then go to Step 12.
12. Evacuate and charge the system with a specified
amount of R-12 or R-134a. Operate the system to
ensure it is cooling properly.
The use of safety when handling or using
refrigerants can never be stressed enough. As
discussed in chapter 6 of this TRAMAN, routinely
think of safety for yourself and coworkers.
Extreme care must be taken to prevent any liquid
refrigerant from coming in contact with the skin and
especially the eyes. A bottle of sterile mineral oil and a
quantity of weak boric acid solution must always be
kept nearby when servicing the air-conditioning
system. Should any liquid refrigerant get into your
eyes, immediately use a few drops of mineral oil to
wash them out; then wash the eyes clean with the weak
boric acid solution. Seek a doctors aid immediately
even though irritation may have ceased. Always wear
safety goggles when servicing any part of the
To avoid a dangerous explosion, never weld,
solder, steam clean, bake body finishes, or use any
excessive amount of heat on or in the immediate area of
any part of the refrigerant system or refrigerant supply
tank, while they are closed to the atmosphere whether
filled with refrigerant or not.
The liquid refrigerant evaporates so rapidly that
the resulting refrigerant gas displaces the air
surrounding the area where the refrigerant is released.
To prevent possible suffocation in enclosed areas,
always discharge the refrigerant into recycling/
reclaiming equipment. Always maintain good
ventilation surrounding the work area.
Although R-12 gas, under normal conditions, is
nonpoisonous, the discharge of refrigerant gas near an
open flame can produce a very poisonous gas. This gas
also attacks all bright metal surfaces. This poisonous
gas is generated when the flame type of leak detector is
used. Avoid inhaling the fumes from the leak detector.
Ensure that R-12 is both stored and installed according
to all federal, state and local ordinances.
When admitting R-12 or R-134a gas into the
cooling unit, always keep the tank in an upright
position. lf the tank is on its side or upside down, liquid
R-12 or R-134 enters the system and may damage the
TRUCK AND BUS AIR CONDITIONING
The cabs of many truck-tractors and long distance
h a u l i n g t r u c k s a n d e a r t h m o v e r c a b s a r e
air-conditioned. Most of this equipment is of the "hang
on" type and is installed after the cab has been made.
Some truck air-conditioning units have two
evaporatorsone for the cab and one for the relief
driver's quarters in back of the driver. Some systems
use a remote condenser, mounted on the roof of the
cab. This type of installation removes the condenser
from in front of the radiator, so the radiator can operate
at full efficiency. This is especially important during
long pulls in low gear.
The system is similar to the automobile air
conditioner and is installed and serviced in the same
The air conditioning of buses has progressed
rapidly. Because of the large size of the unit, most bus
air-conditioning systems use a separate gasoline
engine with an automatic starting device to drive the
compressor. The system is standard in construction
except for the condensing unit. It is made as compact
as possible and generally is installed in the bus, so it
can be easily reached for servicing.