York Millennium YCAJ150, Installation Operation & Maintenance, Page: 86 / 116

86 YORK INTERNATIONAL
PREVENTATIVE MAINTENANCE
It is the responsibility of the owner to provide the neces-
sary daily, monthly and yearly maintenance requirements
of the system.
IMPORTANT
If a system failure occurs due to improper main-
tenance during the warranty period; YORK will
not be liable for costs incurred to return the sys-
tem to satisfactory operation. The following is in-
tended only as a guide and covers only the chiller
unit components. It does not cover other related
system components which may or may not be
furnished by YORK. System components should
be maintained according to the individual
manufacturer’s recommendations as their opera-
tion will affect the operation and life of the chiller.
DAILY MAINTENANCE
It is recommended that the following items be checked
daily.
1. Oil Level – Correct oil level is when oil appears in
either of the compressor oil sight glasses after the
unit has been in operation for about two hours. If it is
necessary to add oil after this operating period, see
item #3 under the ANNUAL MAINTENANCE sec-
tion.
2. Oil Pressure – Oil pressure should be a minimum of
50 PSI (344.7 kPa) above suction pressure. Typical
pressure is 65 - 70 PSI (448.2 to 482.6 kPa).
3. Compressor Superheat – Correct superheat is 10 -
15°F (-12.2 to -9.4°C) measured at the compressor.
4. Operating Pressures and Temperatures – Check to
see that operating pressures and temperatures are
within the LIMITATIONS shown in this book.
WEEKLY MAINTENANCE
It is recommended that the following items be checked
weekly.
1. All items listed under DAILY MAINTENANCE.
2. Color of Compressor Oil – New oil is clear, and if the
system is not contaminated with moisture and/or
foreign material, should retain its new appearance
for a reasonable length of operating time. Discolora-
tion of the oil, either turning darker brown or in some
cases lighter, is an indication of contamination, ba-
sically due to moisture. If it is necessary to charge
oil refer to item #3 under the ANNUAL MAINTE-
NANCE section.
3. Check the refrigerant circuit for leaks.
4. Operating Pressures and Temperatures – Check to
see that operating pressures and temperatures are
within the LIMITATIONS shown in this book.
ANNUAL MAINTENANCE
It is recommended that the following items be checked
annually.
1. All items under WEEKLY MAINTENANCE.
2. Operating Controls – Check to see if controls are
set and operating within the proper limits. See Unit
Controls and OPERATION section of this book.
3. Compressor Oil – Drain, inspect and refill with new
oil. This requires pumping out the compressor. If
possible, this should be done after the unit has been
in operation for some time, when the oil in the crank-
case will contain the least amount of refrigerant. To
pump out the compressor, proceed as follows:
A. Close the suction stop valve.
B. Open the discharge stop valve two turns of the
stem.
C. Operate the compressor until 15 to 20 inches
vacuum (50.7 to 67.5 kPa) is obtained. Do this
by disconnecting the wiring to LLSV and repeat-
edly starting the compressor. Recycle 115VAC
power to the Logic Panel to reduce anti-recycle
time to 2 minutes if needed. The compressor
should in no case be operated under vacuum
conditions for longer than 10 to 15 seconds.
D. Stop the compressor and immediately close the
discharge stop valve. The procedures outlined
in steps (B) and (C) above should be repeated if
the suction pressure rises rapidly to 15 PSIG
(103.4 kPa)or more which would indicate con-
siderable refrigerant remaining in the crankcase
oil. Do not expect to retain 0 PSIG (0 kPa) since
some refrigerant will continually be released from
the oil in the crankcase.