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YORK INTERNATIONAL
the liquid head vents after a period of shutdown. If water
is leaking into the refrigerant, system capacity and effi-
ciency will drop off sharply. If a tube is leaking and water
has entered the system, the cooler and condenser should
be valved off from the rest of the water circuit and drained
immediately to prevent severe rusting and corrosion. If a
tube leak is indicated, the exact location of the leak may
be determined as follows:
1. Allow the system to warm up until a substantial pres-
sure is reached for testing. Dry nitrogen (pressure not
to exceed 12 PSIG) may be admitted to the unit to
increase pressure in the shell. Remove the heads and
listen at each section of tubes for a hissing sound
that would indicate gas leakage. This will assist in
locating the section of tubes to be further investigated.
If the probable location of the leaky tubes has been
determined, treat that section in the following manner
(If the location is not definite, all the tubes will require
investigation).
2. Wash off both tube heads and the ends of all tubes
with water.
NOTE: Do not use carbon tetrachloride for this pur-
pose since its fumes give the same flame
discoloration that the refrigerant does.
3. With nitrogen or dry air, blow out the tubes to clear
them of traces of refrigerant-laden moisture from the
circulation water. As soon as the tubes are clear, a
cork should be driven into each end of the tube. Re-
peat this with all of the other tubes in the suspected
section or if necessary, with all the tubes in the cooler
or condenser. Allow the cooler or condenser to re-
main corked up to 12 or 24 hours before proceeding.
Depending upon the amount of leakage, the corks
may blow from the end of a tube, indicating the loca-
tion of the leakage. If not, it will be necessary to make
a very thorough test with the leak detector.
4. After the tubes have been corked for 12 to 24 hours, it
is recommended that two men working at both ends
of the cooler carefully test each tube one man re-
moving corks at one end and the other at the oppo-
site end to remove corks and handle the leak detec-
tor. Start with the top row of tubes in the section be-
ing investigated, remove the corks at the ends of one
tube simultaneously, and insert the exploring tube for
5 seconds this should be long enough to draw into
the detector any refrigerant gas that might have leaked
though the tube walls. A fan placed at the end of the
cooler opposite the detector will assure that any leak-
age will travel through the tube to the detector.
5. Mark any leaking tubes for later identification.
6. If any tube sheet joints are leaking, the leak should
be indicated by the detector. If a tube sheet leak is
suspected, its exact location may be found by using
a soap solution. A continuous buildup of bubbles
around a tube indicates a tube sheet leak.
COMPRESSOR
For more information covering the MicroComputer Con-
trol Center operation, refer to Section 2.
Maintenance for the compressor assembly consists of
checking the operation of the oil return system and chang-
ing the dehydrator, checking and changing the oil, check-
ing and changing the oil filters, checking the operation of
the oil heater, checking the operation of the oil pump,
and observing the operation of the compressor.
Internal wearing of compressor parts could be a serious
problem caused by improper lubrication, brought about
by restricted oil lines, passages, or dirty oil filters. If the
units are shutting down on (HOT) High Oil Temperature
or Low Oil Pressure (LOP), change the oil filter element.
Examine the oil filter element for the presence of alumi-
num particles. If aluminum particles are noticeable and
the same conditions continue to stop the unit operation
after a new filter element is installed, notify the nearest
YORK office to request the presence of a YORK Ser-
vice Man.
ELECTRICAL CONTROLS
The operating points of the pressure and temperature cut
outs are shown in the Wiring Diagrams. These diagrams
also contain a starting and stopping sequence and tim-
ing sequence diagram.
