Compressor; Leak Detection - Cornelius XAC 1444 Service Training Manual

Compressor

1. Using an ohm meter, check for continuity from compressor terminal C to R and C to S. If the com-
pressor is hot, wait one (1) hour for compressor to cool and recheck. An open internal overload pro-
tector can cause a lack of continuity. If continuity cannot be measured through all windings, the com-
pressor must be replaced.
2. To check the compressor motor for accidental ground, perform a continuity check between terminals
C, R and S to the compressor shell or a copper line of the refrigeration system (do not use a painted
surface). Continuity present, the compressor windings are grounded and the compressor must be
replaced.
If the compressor starts, but trips repeatedly on the overload protector, remember that the overload is
both temperature and current activated. Be sure to check:
S Low voltage
S Undersized supply lines
S High head pressure
S High suction pressure
S Defective capacitors
S Compressor mechanical problems
S Low refrigerant charge

LEAK DETECTION

The new non-chlorine based refrigerants such as [HP - 62/R 404A] require special leak detection devices
other than what has been standard for the CFC's.
While the instruments for leak detection are different, the processes have not changed.
Basics to remember:
1. Look for signs of oil when you visually start your leak check process. Oil is carried with the refriger-
ant. If the oil has leaked out so will the refrigerant.
2. Refrigerant vapor is heavier than air. When leak checking suspect areas, probe below the joints or
connections.
A. Always check the high-side of the system with the compressor operational.
B. Check the low-side of the system, with the system idle.
C. Following a & b will normally allow the highest pressure on each portion of the system for the
best detection.
3. Systems short of refrigerant will show improper operational results in both the freeze and harvest
cycles. Many systems will appear normal in higher operating temperatures and change drastically in
cooler condenser temperatures.
4. Many new and reworked leak detection instruments have the ability to detect CFC's, HCFC's and
the new HFC's by making a simple switch selection. This type of detector will be more sensitive on
one setting than the other. This results in finding some leaks that are so small it may take years be-
fore the actual leak rate would create adverse operating conditions in the product.
A bubble test and/or additives with UV lamp may be the best team for the most positive leak testing
results.
5. Never pressurize a system with oxygen or a mixture of refrigerant and air.
WARNING: Either of these methods may cause a system explosion to occur.
6. Pressurizing systems to leak test should only be done with dry nitrogen. Be sure the regulator set-
ting does not exceed the recommended system pressure.
CAUTION: A full cylinder of nitrogen will have pressure of approximately 2700 PSI.
7. Failure to correct leaks will also cause shorter compressor life as a result of the higher operating
temperatures. Always check the total system for leak, there may be more than one leak.
TP00952 34
Xtreme Ice Training Manual
October 17, 2005