44 Auto Heating & Air Conditioning
Dye
Dye is used to locate minute leaks. The dye is injected
into the refrigeration system and allowed to circulate for
a few minutes. Some of the dye will leak out along with
any refrigerant and stain the components at the site of
the leak.
Older refrigerant dyes were colored orange and were
contained in a small can resembling a one pound refriger-
ant can. The can was connected to the system low side
through the gauge manifold. With the system operating,
the dye was drawn into the system. After the dye circu-
lated for a few minutes, the technician could look for the
presence of orange dye. Dye cans are still used in some
areas.
Modern dye injectors are designed to inject a fl uores-
cent dye directly into the refrigeration system, Figure 3-9A.
The injector is attached to one of the system service ports
and the handle is turned to force the dye into the system.
After the dye has circulated through the operating system
for a few minutes, the technician shines an ultraviolet light,
such as the one shown in Figure 3-9B, on the suspected
leak points. If any of the dye has leaked out, it will glow
under the ultraviolet light.
Halide Flame Detector
The halide fl ame detector is not as accurate as an
electronic detector. It will, however, detect relatively large
refrigerant leaks. The halide detector consists of a propane
cylinder attached to a burner, Figure 3-10. A sensing hose
draws refrigerant from the suspected leak area. A copper
reaction plate improves the combustion process between
the refrigerant, propane, and air.
Warning: Halide fl ame leak detectors are
very dangerous. They should only be used
if no other detection method is available. A
refrigerant identifi er should be used before using a
halide detector to reduce the chance of fi re or an
explosion. They should only be used with R-12 systems.
To use a halide leak detector, light the burner. After
a few minutes operation, the reaction plate will glow dull
red. Adjust the fl ame as necessary, then pass the free end of
the sensing hose under any suspected leak areas. If refriger-
ant is present, the fl ame will change color. Small leaks will
cause the fl ame to develop a greenish tint. A large leak will
cause the fl ame to turn bright blue.
When the leak detecting process is fi nished, tightly
close the propane valve and allow the tester to cool before
returning it to storage. The propane valve should be closed
tightly when the fl ame detector is not in use.
Soap Solution
The soap solution method will fi nd large leaks only,
and should not be relied on to locate small leaks or leaks in
inaccessible locations. It is primarily used to confi rm what
appears to be an obvious leak. Soap solution is sometimes
the only detection method available if a system has been
fi lled with a refrigerant other than R-134a or R-12.
Figure 3-9. A—Dyes are injected into the system using a device
such as the one shown here. B—A black light will illuminate the
dye as it leaks out with the refrigerant.
A
B
Figure 3-10. The fl ame type leak detector, while seldom used
today, will detect most medium sized leaks. It must be used
carefully to prevent false readings and maintain shop safety.
(Ford)
Burner
Reaction
plate
Search
hose
Propane
cylinder
Valve
Detector
unit