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ntents- Index
vacuum) to plus pressure inside the hoses and all components. The
refrigerant and refrigeration oil are trying to escape from the system at
all times.
Technicians frequently add refrigerant to a system, replacing refriger-
ant seepage 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 lookfor, 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
moisture absorbing capacity of any desiccant material is limited and
cannot be measured. For that reason, replace the receiver-drier or accu-
mulator. Then evacuate the system for an hour and recharge with refrig-
erant.
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 troubleshooting with the answers he gave you. Problems your
inspection may have turned up are a very low refrigerant charge, a contami-
nated system or defective compressor. Those are not quick fix jobs.
On the other hand, you might have found enough debris on the condenser fin
surface 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, troubleshooting and repair. In
Chapter 9
we will describe complete system purging, evacuation, flushing and
recharging.
Conclusion