possible causes associated with each air-conditioning
component. This is by no means a complete list, so you
should have the manufacturers vehicle repair manual
A thumping noise in the compressor or a cool and
sweating compressor suction line accompanied by no
cooling is usually caused by too much refrigerant in the
system. If there is no moisture in the system, the excess
refrigerant should be removed and stored for proper
disposal. If moisture is present, you must discharge,
evacuate, and recharge the system.
The condenser unit could have clogged fins that
limit the cooling ability of the unit. This could be caused
by bugs, leaves, or other debris caught in the tins. This
can be corrected by using air pressure to blow out the
coils, Check for any icy or frosty spots on the condenser.
An abnormally cold spot usually indicates partial
restriction inside the condenser coils at that point.
Restrictions are normally caused by foreign matter.
Correct this condition by discharging and purging the
The evapator is normally maintenance free for the
life of a vehicle. If the evaporator does develop a leak,
it will be necessary to remove the assembly for repair.
An evaporator is repaired in the same manner as a
radiator. If the evaporator does not get the right amount
of refrigerant, the expansion valve is most likely at fault.
The most common malfunction in the expansion
valve is icing caused by moisture in the air-conditioning
system. The system must be discharged and evacuated
to remove all moisture. On occasion, the expansion
valve may stick open or closed; in this case, you must
replace the valve.
The receiver/drier may become saturated with
moisture or the filter may become restricted. If the
receiver/drier is saturated or restricted, replace it. For
any of these repairs,
comply with the appropriate
AIR-CONDITIONING SYSTEM FOR
Approximately 80 percent of all air-conditioning
service work consists of your inspecting for and
repairing leaks. Many leaks will be located at points of
connection and are caused by vehicle vibration. They
may only require the retightening of a flare connection
or a clamp. Occasionally, a hose will rub on a structural
part to create a leak, or a hose may deteriorate and
require replacement. The compressor shaft seal may
also require. occasional replacement. Anytime the
system requires more than one-half pound of refrigerant
after operating during one season, a serious leak is
indicated that you must locate and repair. The following
information covers a few of the various means of
When any tests or repairs are being made
on a charged air-conditioning system, always
wear adequate eye protection.
INTERNALLY CHARGED DETECTOR
This detector is a specially colored leak detector
available in a pressurized can and mixed with R-12. It
can be introduced into the air-conditioning system with
regular charging equipment. When a leak occurs in the
system, a bright red-orange spot appears at the point of
leakage and remains until it is wiped off. The internal
leak detector remains in the system and will spot future
leaks in the same manner. A sticker is usually placed
under the vehicle hood to indicate that the system is
charged with a leak detector.
The bubble detector is a solution applied externally
at suspected leak points. Leaking refrigerant will cause
the detector to form bubbles and foam.
This instrument indicates leaks electronically by
flashing a light or sounding an alarm. There are several
different types of electronic detectors. Directions for
using the instruments are furnished by the manufacturer.