III-102
Technicians frequently add refrigerant to a system, replacing refrigerant seep-
age through system connections or fittings. If the system has been maintained
regularly (every three to six months), adding a small amount of refrigerant may
result in normal system function. However, the best procedure is to check all
connections and look for, find and repair any leaks before adding refrigerant.
When your leak detector indicates the presence of a leak, you can·t tell how
long the system has been leaking. Finding one leak doesn·t mean there are not
others. Until you have some AC system work experience, it will be hard to guess
how much refrigerant may have leaked. If you have to top a system off with a half
pound of refrigerant or more, adding refrigerant is not the answer.
Find the leak. Recover all of the refrigerant and repair the system. The mois-
ture absorbing capacity of any desiccant material is limited and cannot be mea-
sured. For that reason, replace the receiver-drier or accumulator. Then evacuate
the system for an hour and recharge with refrigerant.
When a compressor shaft seal has leaked oil and the refrigerant charge is a little
low, the shaft seal may have leaked because the air conditioner was not used. The
seal can get a little out of round from the weight of the crankshaft and leak above
the shaft. Running the compressor may cause the seal to swell and close up the
leak. The shaft rotation exerts force all around the seal and puts life back into it.
To prevent this from happening, manufacturers recommend regular AC system
operation a minimum of every couple of weeks even in cool weather.
Keep in mind that the compressor can cause a vacuum inside the system if there
is a restriction in the system. That means it can suck air and moisture inside under
some conditions. It will pull these contaminants in through the same space where
refrigerant and refrigerant oil has leaked out.
Conclusion
What could the air conditioning problem and it·s cause have been at the beginning of
this chapter? The operator was in a hurry, but you were able to start your troubleshoot-
ing with the answers he gave you. Problems your inspection may have turned up are
a very low refrigerant charge, a contaminated system or defective compressor. Those
are not quick fix jobs.
On the other hand, you might have found enough debris on the condenser fin sur-
face to boost high side pressures to an abnormal level during the hottest part of the day.
So the Trinary™ or high pressure switch would cut out from high pressure—but reset
itself. You cleaned the condenser, added a half pound of refrigerant and AC system
pressures and function returned to normal. Service and repair took a half hour. But
there was no way to tell without using your knowledge and experience. By now you
are pretty familiar with AC system problems, the reasons for some of them, trouble-
shooting and repair. In Chapter 9 we will describe complete system purging, evacua-
tion, flushing and recharging.
Conclusion
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