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Scroll Compressor Rotational Direction
Scroll compressors only compress in one rotational direction.
Three-phase compressors rotate in either direction depending
upon phasing of the power to L1, L2, and L3. Since there is
a 50/50 chance of connecting power to cause rotation in the
reverse direction, verify that the compressor rotates in the
proper direction after the system is installed. If the compressor
is rotating properly, suction pressure drops and discharge
pressure rises when the compressor is energized. If the
compressor is rotating in reverse, the sound level is louder and
current draw is reduced substantially. After several minutes of
operation, the compressor’s internal protector trips.
All three-phase compressors are wired the same internally.
Therefore, once the correct phasing is determined for a specific
system or installation, connecting properly phased power leads
to the same terminals should maintain proper rotation direction.
Perform the Following Procedure:
1 .
At the keypad, set the cooling setpoint low enough so
that the controller will call for cooling.
2 .
Verify that compressor #1 starts. If the compressor motor
hums but does not run, verify that it is getting three-
phase power.
3 .
The compressor should operate continuously while there
is a call for cooling. If the compressor cycles on and off
on its low pressure switch, perform the following:
a .
Verify that the circuit is not short of refrigerant.
b .
Check for low airflow across the evaporator coil.
c. Check for clogged filters.
d .
Check for restricted ductwork.
e .
Check for very low temperature return air entering
the unit.
f. Verify that the liquid line components, expansion
valve, and distributor tubes are feeding the
evaporator coil.
g. Verify that all air handling section panels are
closed.
4 .
Verify that the condenser fans are cycling and rotating
properly (blowing air upward). When the compressor
starts, at least one condenser fan should also start.
5 .
Check the oil level in the compressor sightglass. If
low oil is observed, it is possible that liquid refrigerant
is returning to the compressor. Check the suction
superheat, see “Expansion Valve Superheat Adjustment”
below. It should be between 10°F (5.5°C) and 13°F
(7.2°C). See “Expansion Valve Superheat Adjustment”
below.
6 .
Verify that the condenser refrigerant subcooling at full
capacity is between 13°F and 20°F.
Checking Subcooling
Following are recommendations for checking subcooling:
1 .
Run unit until it reaches steady state. Close the unit
section doors. Running the unit with its doors open will
affect system operation.
2 .
Measure the discharge gas pressure at the compressor
discharge gauge port with an accurate gauge. Use this
pressure to determine the saturation temperature of the
refrigerant.
3 .
Measure liquid temperature accurately by attaching
a thermocouple to the liquid line tube leaving the
condenser coil. Insulate the tube and thermocouple for
more accurate results.
4 .
Subtract the measured liquid temperature from the
saturation temperature to determine the subcooling.
5 .
As a general rule, high subcooling indicates that the
circuit is low on charge. Low subcooling generally
indicates that the circuit has too much charge.
NOTICE
Venting refrigerant to atmosphere is not allowed per most
local laws and/or codes.
IM 1058-8 • MAVERICK II ROOFTOP SYSTEMS
94
www.DaikinApplied.com
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Содержание MPS015 F
Страница 70: ...Figure 64 VAV Control Inputs IM 1058 8 MAVERICK II ROOFTOP SYSTEMS 70 www DaikinApplied com Wiring Diagrams ...
Страница 80: ...Figure 70 CAV Power IM 1058 8 MAVERICK II ROOFTOP SYSTEMS 80 www DaikinApplied com Wiring Diagrams ...
Страница 81: ...Figure 70 continued CAV Power Wiring Diagrams www DaikinApplied com 81 IM 1058 8 MAVERICK II ROOFTOP SYSTEMS ...
Страница 82: ...Figure 71 CAV Control Inputs IM 1058 8 MAVERICK II ROOFTOP SYSTEMS 82 www DaikinApplied com Wiring Diagrams ...
Страница 86: ...Figure 76 Energy Recovery IM 1058 8 MAVERICK II ROOFTOP SYSTEMS 86 www DaikinApplied com Wiring Diagrams ...