WD Catalog 2018

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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 look

for, find and repair

any leaks before adding refrigerant. When your leak detector in

dicates the presence of a leak, you can’t tell

how long the system has be

en leaking. Finding one leak doesn’t mean

there are not others. Until you have some AC syste

m 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 th

e answer.

Find the leak. Re

cover 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