Transcript Two-Stage Scroll Compressors

Two-Stage Copeland
Scroll Compressors
External view
• 1st stage = 67%
• 2nd stage = 100%
• Used in 17 SEER
AC.
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Customer Experience
• Majority of run hours @ 67%
• Delivers steady state cooling.
• Eliminates temperature peaks
& valleys from compressor
cycling.
• Better humidity control.
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How does it work?
• Solenoid opens or closes a
port on the internal scrolls.
• Valve is actually a ring that
rotates.
• Ring opens or closes the
bypass port.
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Internal assembly
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1st Stage Position
• Solenoid is NOT energized.
• Port is OPEN.
• Only 2/3 of scroll compresses
refrigerant.
• The other 1/3 is bypassed thru
the open port.
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Solenoid: “unpowered”
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Port open
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Port open
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2nd Stage Position
• Solenoid is energized w 24 volts dc.
• Ring rotates & closes the port.
• The entire scroll capacity is
delivered.
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Scroll internals
• Solenoid operates on DC voltage.
• Initial inrush is 18 to 28 volts DC.
• Holding voltage is less.
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Solenoid: “powered”
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Port closed
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Port closed
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Staging Control Wiring
• Separate wiring to terminal
block on compressor shell.
• Connects integrated
compressor control to internal
solenoid.
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Checking Solenoid
Use your
ohmmeter.
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Solenoid Molex Plug
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Molex unplugged
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Placement of probes
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“Good” Ohm reading
32 to 60 ohms.
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Ohm check on Molex plug
• If resistance is infinite, the
solenoid is electrically “open”.
• Compressor never operates on
2nd stage.
• The fix? Replace the
compressor.
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