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direction.
Verification of proper rotation is done by observing suction and discharge pressures when the compressor is
operating. A decrease in discharge pressure and an increase in suction pressure indicate reverse rotation.
After several minutes of operation the compressor internal linebreak will de-energize the compressor. In order
to correct this situation, disconnect the power and switch any two power leads at the unit contactor. NEVER
switch leads directly at the compressor.
Internal wiring of the compressor is consistent with the direction of rotation. As a result, once the correct
phasing is determined for a specific system or installation, connecting properly phased leads to the same
terminals should maintain proper rotation direction.
A phase monitor can be applied to ensure correct rotation when power is initiated. Labeling for three phase
models is U, V, W and for single phase C (common), S (start) and R (run). Each compressor is labeled with
the appropriate sequence. As showed in wiring diagram, the line phases R (L1), S (L2) and T (L3) should be
connected to terminals U, V and W, respectively.
Spade terminals type
Screw terminals type
Figure 3-4 Compressor Terminal
3.9 Terminal cover and clip
The terminal cover and clip should be installed prior to operation of the compressor. To ensure the cover is
properly installed, a double check should be done to make sure the lead wires are not pinched under it.
3.10 Preliminary Running
In order to lubricate the compressor movement parts, the compressor should be operated at least 3 seconds
within 15min after refrigerant charged. Check the following items:
1) To check whether abnormal sound or abnormal tube vibration occurs.
2) To check whether refrigerant leaks from the connection part.
3) To check the cooling effect.
3.11 Start Compressor with Balanced Pressure
The OFF cycle setting of compressor should be at least 3 minutes which is the period to balance the high
side and low side pressure of system. Especially for single phase models, starting the compressor with
balanced pressure should be always followed.
3.12 Servicing Scroll Compressors
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