Mazda CT-L1005, Training Manual

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Diagnosis and Repair Basic Climate Control
Leak Testing
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The amount of refrigerant in automotive A/C systems has been steadily decreasing. The
lower fill volumes mean that leaks present in the system are going to be noticeable
earlier, as a reduction in cooling performance, compared to previous systems filled with
more refrigerant.
•
An automotive A/C system has weak spots that cannot be easily avoided. For example,
because the compressor is mounted on the engine, which has to move relative to the
vehicle body, the refrigerant lines need to be flexible. These flexible hoses allow a small
amount of refrigerant to leak. The connections between the various components also
have a small leakage rate. The single largest source of leakage is the shaft seal on the
compressor.
•
Compare all of these potential leaks to a stationary A/C unit, such as your household
refrigerator. In a refrigerator, which has the same function, and the same basic
components, there is no need to use flexible hoses, and there is no need to have
serviceable connections between the various components. All of the connections are
soldered, and the result is a system that rarely requires service, and where leak
checking plays a very unimportant role. The normal seepage of an automotive A/C
system cannot be stopped, and these minuscule leaks should not be taken into
consideration during leak testing.
•
Leaks that have caused a reduction in cooling performance must be found and repaired.
There are a number of ways to check a system for a leak. If there is still refrigerant in the
system and a leak is suspected, the complete refrigerant circuit can be visually inspected
for oily accumulation. Some compressor oil will escape with the refrigerant, and this can
be a good indicator of a leak.
•
A leak detection solution can be sprayed on the suspected leak, and bubbles will form.
•
An electronic leak detector can also be used to detect the refrigerant leaks.
•
The MX-5 and the Tribute use compressor oils with an added dye, which is visible when
an ultraviolet lamp is shone on it.
•
If there is no refrigerant left in the system, and the leak cannot be located visually, then
refrigerant will need to be added.
•
Most A/C service machines also have a leak detection function. A vacuum is applied to
the system, and if the vacuum does not hold for a specified amount of time, then this
indicates a leak in the system. Of course this still does not remove the need to pinpoint
the location of the leak using one of the other methods mentioned above.
Curriculum Training 05-4