ASPT Service Manual
Table Of Contents
- IMPORTANT INFORMATION
- PRODUCT IDENTIFICATION
- Checking Voltage
- Checking Wiring
- Checking Thermostat And Wiring
- Thermostat Wiring
- Checking Transformer And Control Circuit
- Checking Contactor And/Or Relays
- Checking Contactor Contacts
- Checking Fan Relay Contacts
- Checking Loss Of Charge Protector (Heat Pump Models)
- Checking High Pressure Control
- Checking Low Pressure Control
- Copeland Comfort Alert™ Diagnostics - 3-Wire module
- Copeland Coresense™ Diagnostics - 3-Wire module
- Checking Capacitor
- Resistance Check Using A Digital Multi-Meter
- Capacitance Check Using A Digital Multi-Meter (In Capacitance Mode)
- Testing a Run Capacitor Under Load
- Checking Outdoor Fan and Blower Motors (PSC Motors)
- Checking Fan and Blower Motor (ECM Motors)
- Checking ECM Motor Windings
- ECM CFM Adjustments MBE/AEPF
- Blower Performance Data
- Checking High Efficiency Motors
- EEM Blower Replacement
- MBR/AR*F Electronic Blower Time Delay Relay
- Checking Compressor
- Resistance Test
- Ground Test
- Unloader Test Procedure
- Operation Test
- Checking 3-Phase Scroll Compressor Rotation
- Testing Crankcase Heater (Optional Item)
- Checking Reversing Valve and Solenoid
- Testing Defrost Control
- Testing Defrost Thermostat
- Checking Heater Limit Control(s)
- Checking Heater Elements
- Electric Heater (Optional Item)
- Checking Heater Limit Control(s)
- Checking Heater Elements
- Refrigeration Repair Practice
- Leak Testing (Nitrogen or Nitrogen-Traced)
- Evacuation
- Charging
- Checking Compressor Efficiency
- Overfeeding
- Underfeeding
- Checking Superheat
- Subcooling on Expansion Valve System
- Checking Expansion Valve Operation
- Checking Restricted Liquid Line
- Overcharge Of Refrigerant
- Non-Condensables
- Compressor Burnout
- Refrigerant Piping
- Duct Static Pressures
- Single Piece Air Handler External Static
- Two Piece Air Handler External Static Pressure
- Furnace External Static Pressure
- Periodic Maintenance
PRODUCT DESIGN
54
The ASX [16 & 18], ASZ [16 & 18], DSX[16 & 18] and
DSZ [16 & 18] series split system units use a two-stage
scroll compressor. The two-step modulator has an internal
unloading mechanism that opens a bypass port in the rst
compression pocket, eectively reducing the displacement
of the scroll. The opening and closing of the bypass port is
controlled by an internal electrically operated solenoid.
The ZPS/ZRS two-step modulated scroll uses a single step
of unloading to go from full capacity to approximately 67%
capacity. A single speed, high eciency motor continues
to run while the scroll modulates between the two capacity
steps.
FIGURE A
A scroll is an involute spiral which, when matched with a
mating scroll form as shown, generates a series of crescent
shaped gas pockets between the two members.
During compression, one scroll remains stationary (xed
scroll) while the other form (orbiting scroll) is allowed to
orbit (but not rotate) around the rst form.
As this motion occurs, the pockets between the two forms
are slowly pushed to the center of the two scrolls while
simultaneously being reduced in volume. When the pocket
reaches the center of the scroll form, the gas, which is now
at a high pressure, is discharged out of a port located at
the center.
During compression, several pockets are being
compressed simultaneously, resulting in a very smooth
process. Both the suction process (outer portion of the
scroll members) and the discharge process (inner portion)
are continuous.
Some design characteristics of the Compliant Scroll
compressor are:
• Compliant Scroll compressors are more tolerant of
liquid refrigerant.
compressor is more tolerant of liquid refrigerant,
• “Ultratech” Series scroll compressors use “POE” or
polyolester oil which is NOT compatible with mineral
oil based lubricants like 3GS. “POE” oil must be used if
additional oil is required.
• Compliant scroll compressors perform “quiet” shutdowns
that allow the compressor to restart immediately without
the need for a time delay. This compressor will restart
even if the system has not equalized.
Information Manual.
Capacity Control - Legacy Models
During the compression process, there are several pockets
within the scroll that are compressing gas. Modulation is
achieved by venting a portion of the gas in the rst suction
pocket back to the low side of the compressor thereby
reducing the eective displacement of the compressor.
See Figure A. Full capacity is achieved by blocking these
vents, increasing the displacement to 100%. A solenoid in
the compressor, controlled by an external 24-volt ac signal,
moves the slider ring that covers and uncovers these
vents. The vent covers are arranged in such a manner that
the compressor operates somewhere around 67% capacity
when the solenoid is not energized and 100% capacity
when the solenoid is energized. The loading and unloading
of the two step scroll is done “on the y” without shutting
o the motor between steps. See Figure B below. The
unloaded mode default was chosen for two reasons: