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Place the Unit Switch in the control panel to the
ON position. As each compressor cycles on,
ensure that the discharge pressure rises and
the suction pressure decreases. If this does
not occur, the compressor being tested is oper-
ating in the reverse direction and must be cor-
rected. After verifying proper compressor rota-
tion, turn the Unit Switch to "OFF."
The cooling setpoint may need to be tem-
porarily lowered to ensure all compres-
sors cycle "ON."
This unit uses scroll compressors which
can only operate in one direction. Fail-
ure to observe these steps could lead to
compressor failure.
G 6. YCUL00125 - YCUL0275 units only – Turn sys-
tem 1 off and system 2 on (refer to Option 2 un-
der "Unit Keys" section for more information on
system switches.)
Place the Unit Switch in the control panel to the
ON position. As each compressor cycles "ON,"
ensure that the discharge pressure rises and
the suction pressure decreases. If this does
not occur, the compressor being tested is oper-
ating in the reverse direction and must be cor-
rected. After verifying proper compressor rota-
tion, turn the Unit Switch to "OFF."
The cooling setpoint may need to be tem-
porarily lowered to ensure all compres-
sors cycle "ON."
G 7. After verifying compressor rotation, return the Unit
Switch to the OFF position and ensure that both
Systems are programmed for "ON" (refer to Op-
tion 2 under "Unit Keys" section for more informa-
tion on system switches).
INITIAL START-UP
After the preceding checks have been completed and
the control panel has been programmed as required in
the pre-startup checklist, the unit may be placed into
operation.
G 1. Place the Unit Switch in the control panel to the
ON position.
YORK INTERNATIONAL
G 2. The first compressor will start and a flow of re-
frigerant will be noted in the sight glass. After
several minutes of operation, the vapor in the
sight glass will clear and there should be a solid
column of liquid when the TXV stabilizes.
G 3. Allow the compressor to run a short time, being
ready to stop it immediately if any unusual noise
or adverse conditions develop.
G 4. Check the system operating parameters. Do this
by selecting various displays such as pressures
and temperatures and comparing these readings
to pressures and temperatures taken with mani-
fold gauges and temperature sensors.
G 5. With an ammeter, verify that each phase of the
condenser fans and compressors are within the
RLA as listed under Electrical Data.
CHECKING SUPERHEAT AND SUBCOOLING
The subcooling and superheat should always be checked
when charging the system with refrigerant.
When the refrigerant charge is correct, there will be no
vapor in the liquid sight glass with the system operating
under full load conditions, and there will be 15°F (8.34°C)
subcooled liquid leaving the condenser.
An overcharged system should be guarded against. The
temperature of the liquid refrigerant out of the condenser
should be no more than 15°F (8.34°C) subcooled at de-
sign conditions.
The subcooling temperature of each system can be cal-
culated by recording the temperature of the liquid line at
the outlet of the condenser and subtracting it from the
liquid line saturation temperature at the liquid stop valve
(liquid line saturation temp. is converted from a tempera-
ture/pressure chart).
Example:
Liquid line pressure =
202 PSIG converted to
minus liquid line temp.
SUBCOOLING =
The subcooling should be adjusted to 15°F at design
conditions.
G 1. Record the liquid line pressure and its correspond-
ing temperature, liquid line temperature and
subcooling below:
SYS 1
Liq Line Press = _______ _______ PSIG
Saturated Temp = _______ _______ °F
Liq Line Temp = _______ _______ °F
Subcooling = _______ _______ °F
FORM 150.63-NM2
2
102°F
- 87°F
15°F
SYS 2
93
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