YORK INTERNATIONAL
37
FORM 150.40-NM25
SINGLE CIRCUIT UNITS
PREVENTIVE MAINTENANCE
It is the responsibility of the owner to provide the neces-
sary daily, monthly and annual maintenance require-
ments of the system. IMPORTANT – If a system failure
occurs due to improper maintenance during the warranty
period, YORK will not be liable for costs incurred to re-
turn the system to satisfactory operation. The following
is intended 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 ac-
cording to the individual manufacturers’ recommenda-
tions as their operation 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 section.
2. Oil Pressure – Oil pressure should be a minimum of
50 PSI (344 kPa) above suction pressure. Typical
pressure is 65-70 PSI (447.8-482.3 kPa).
3. Compressor Superheat – Correct superheat is 10-
15°F (5.5-8.33°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 for-
eign material, should retain its new appearance for a
reasonable length of operating time. Discoloration of
the oil, either turning darker brown or in some cases
lighter, is an indication of contamination, basically due
to moisture. If it is necessary to charge oil refer to
item #3 under the ANNUAL MAINTENANCE section.
3. Check the refrigerant circuit for leaks.
ANNUAL MAINTENANCE
It is recommended that the following items be checked
annually.
1. All items listed under WEEKLY MAINTENANCE.
2. Operating Controls – Check to see if controls are set
and operating within the proper limits. See Unit Con-
trols and OPERATION section of this book.
3. Compressor Oil – Drain, inspect and refill with new
oil. This requires pumping out the compressor. If pos-
sible, 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 is obtained. Do this by disconnecting the
wiring to LLSV and repeatedly starting the com-
pressor. Recycle 115VAC power to the Logic Panel
to reduce anti-recycle time to 2 min. if needed. The
compressor should in no case be operated under
vacuum conditions for longer than 10 to 15 sec-
onds.
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 kPa)
or more which would indicate considerable refrig-
erant remaining in the crankcase oil. Do not ex-
pect to retain 0 PSIG (0 kPa), since some refriger-
ant will continually be released from the oil in the
crankcase.
E. After pumping down the compressor, wait until the
pressure builds up to 2 (13.7 kPa) or 3 PSIG (20.7
kPa) before opening up any part of the hermetic
compressor.
F. Open the oil drain valve slowly and drain as much
oil from the compressor as possible.
G. Examine the oil for any metal particles which would
indicate wear on the bearings, crankshaft or con-
necting rods. If metal particles are found, the need
for closer examination by factory service person-
nel is indicated.
