SS-SVX11K-EN
113
NNoottee:: Interchanging "Load" side power wires at the
contactors only affects the individual fan
rotation. Ensure that the voltage phase
sequence at the main terminal block 1TB1 is
ABC as outlined in the "Electrical Phasing"
section.
Some Motors are Rotating Backward
1. Turn the field supplied disconnect switch or circuit
protector switch that provides power to the
condensing unit to the "Off" position. Lock the
disconnect switch in the open position while
working at the unit.
2. If the unit main power phase sequence is correct,
rotation of an individual motor will be backwards if
any two leads are interchanged between the unit
main power and the motor. Verify that wiring from
the unit main power to the motor is per the unit
wiring diagram. Refer to the illustration in Figure 63
for the compressor terminal/phase identification.
Compressor damage could occur if a compressor
runs backwards for a very short period of time.
Subcooling
The outdoor ambient temperature must be between
65ºF and 105ºF and the relative humidity of the air
entering the evaporator must be above 40 percent.
When the temperatures are outside of these ranges,
measuring the operating pressures can be
meaningless.
With the unit operating at “Full Circuit Capacity”,
acceptable subcooling ranges between 8ºF to 16ºF.
Measuring Subcooling
NNoottee:: System charging is done by using the System
Charging Chart. Do not attempt to charge the
system based on subcooling.
• At the liquid line service valve, measure the liquid
line pressure. Using a Refrigerant R-410A pressure/
temperature chart, convert the pressure reading
into the corresponding saturated temperature.
• Measure the actual liquid line temperature as close
to the liquid line service valve as possible. To
ensure an accurate reading, clean the line
thoroughly where the temperature sensor will be
attached. After securing the sensor to the line,
insulate the sensor and line to isolate it from the
ambient air.
NNoottee:: Glass thermometers do not have sufficient
contact area to give an accurate reading.
• Determine the system subcooling by subtracting
the actual liquid line temperature from the
saturated liquid temperature.
Measuring Superheat
• Measure the suction pressure at the outlet of the
evaporator as close to the expansion valve bulb
location as possible.
• Measured the suction line temperature as close to
the expansion valve bulb, as possible.
• Using a Refrigerant/Temperature chart, convert the
pressure reading to a corresponding saturated
vapor temperature.
NNoottee:: On many Trane fan/coil units, an access valve
is provided close to the expansion valve bulb
location. This valve must be added on
climate changers and other evaporators.
• Subtract the saturated vapor temperature, from the
actual suction line temperature. The difference
between the two temperatures is known as
“superheat”.
Compressor Oil
NNOOTTIICCEE
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RAUJ unit and replacement compressors ship fully
charged with POE oil from the factory. The scroll
compressor uses POE oil (OIL00079 for a quart
container or OIL00080 for a gallon container) without
substitution. The appropriate oil charge for a 7.5 Ton
scroll compressor is 6.3 pints. For 9 through 15 Ton
light commercial scroll compressors is 7 pints. For a 15
and 20 Ton large commercial scroll compressors (80 to
120 ton units), use 14.2 pints.
Compressor Crankcase Heaters
Table 35. Heater information
Compressor
Configuration and Size
Heater
(watt)
Quantity (per
compressor)
CSHD 7.5 to 15 tons 90 1
CSHN 15 to 20 tons 160 1
SSttaarrtt--UUpp
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