To check switch:
1. Turn off all power to unit.
2. Disconnect leads on switch.
3. Apply ohm meter leads across switch. You should have
continuity on a good switch.
Step 12—Copeland Scroll Compressor (Puron Refriger-
ant)
The compressor used in this product is specifically designed to
operate with Puron (R-410A) refrigerant and cannot be inter-
changed.
The compressor is an electrical (as well as mechanical) device.
Exercise extreme caution when working near compressors. Power
should be shut off, if possible, for most troubleshooting tech-
niques. Refrigerants present additional safety hazards.
Wear safety glasses and gloves when handling refrigerants.
Keep torches and other ignition sources away from refriger-
ants and oils. Failure to follow this warning can cause a fire,
serious injury, or death.
The scroll compressor pumps refrigerant throughout the system by
the interaction of a stationary and an orbiting scroll. The scroll
compressor has no dynamic suction or discharge valves, and it is
more tolerant of stresses caused by debris, liquid slugging, and
flooded starts. The compressor is equipped with an anti-rotational
device and an internal pressure relief port. The anti-rotational
device prevents the scroll from turning backwards and replaces the
need for a cycle protector. The pressure relief port is a safety
device, designed to protect against extreme high pressure. The
relief port has an operating range between 550 and 625 psi
differential pressure.
The Copeland scroll compressor uses Mobil 3MA POE oil.
This is the only oil allowed for oil recharge.
Step 13—Refrigerant System
This step covers the refrigerant system of the 50XZ, including the
compressor oil needed, servicing systems on roofs containing
synthetic materials, the filter drier and refrigerant charging.
REFRIGERANT
This system uses Puron (R-410A) refrigerant which has
higher operating pressures than R-22 and other refrigerants.
No other refrigerant may be used in this system. Gauge set,
hoses, and recovery system must be designed to handle
Puron. If you are unsure consult the equipment manufacturer.
Failure to use Puron compatible servicing equipment or
replacement components may result in property damage or
injury.
COMPRESSOR OIL
The compressor in this system uses a polyolester (POE) oil, Mobil
3MA POE. This oil is extremely hygroscopic, meaning it absorbs
water readily. POE oils can absorb 15 times as much water as other
oils designed for HCFC and CFC refrigerants. Take all necessary
precautions to avoid exposure of the oil to the atmosphere.
SERVICING SYSTEMS ON ROOFS WITH SYNTHETIC MA-
TERIALS
POE (polyolester) compressor lubricants are known to cause long
term damage to some synthetic roofing materials.
Exposure, even if immediately cleaned up, may cause embrittle-
ment (leading to cracking) to occur in one year or more. When
performing any service that may risk exposure of compressor oil to
the roof, take appropriate precautions to protect roofing. Proce-
dures which risk oil leakage include, but are not limited to,
compressor replacement, repairing refrigerant leaks, replacing
refrigerant components such as filter drier, pressure switch, me-
tering device, coil, accumulator, or reversing valve.
Synthetic Roof Precautionary Procedure
1. Cover extended roof working area with an impermeable
polyethylene (plastic) drip cloth or tarp. Cover an approximate
10 X 10 ft. area.
2. Cover area in front of the unit service panel with a terry cloth
shop towel to absorb lubricant spills and prevent run-offs, and
protect drop cloth from tears caused by tools or components.
3. Place terry cloth shop towel inside unit immediately under
component(s) to be serviced and prevent lubricant run-offs
through the louvered openings in the unit base.
4. Perform required service.
5. Remove and dispose of any oil contaminated material per
local codes.
LIQUID LINE FILTER DRIER
The biflow filter drier is specifically designed to operate with
Puron. Use only factory-authorized components. Filter drier must
be replaced whenever the refrigerant system is opened. When
removing a filter drier, use a tubing cutter to cut the drier from the
system. Do not unsweat a filter drier from the system. Heat
from unsweating will release moisture and contaminants from
drier into system.
PURON (R-410A) REFRIGERANT CHARGING
Refer to unit information plate and charging chart. Some R-410A
refrigerant cylinders contain a dip tube to allow liquid refrig-
erant to flow from cylinder in upright position. For cylinders
equipped with a dip tube, charge Puron units with cylinder in
upright position and a commercial metering device in manifold
hose. Charge refrigerant into suction-line.
Step 14—System Information
LOSS OF CHARGE SWITCH
The loss of charge switch is a protective device wired into control
circuit (low voltage). It shuts off the compressor if abnormally low
pressures are present in the refrigeration circuit.
NOTE:
Because these switches are attached to refrigeration
system under pressure, it is not advisable to remove this device for
troubleshooting unless you are reasonably certain that a problem
exists. If switch must be removed, remove and recover all system
charge so that pressure gauges read 0 psi. Never open system
without breaking vacuum with dry nitrogen.
CHECK DEFROST THERMOSTAT
There is a liquid header with a brass distributor and feeder tube
going into outdoor coil. At the end of 1 of the feeder tubes, there
is a 3/8-in. OD stub tube approximately 3 in. long. (See Fig. 30)
The defrost thermostat should be located on stub tube. Note that
there is only 1 stub tube used with liquid header, and on most units
it is the bottom circuit.
The defrost thermostat signals heat pump that conditions are right
for defrost or that conditions have changed to terminate defrost. It
is a thermally actuated switch clamped to outdoor coil to sense its
temperature. Normal temperature range is closed at 30° ± 3°F and
open at 80° ± 5°F.
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