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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.
XIII. REFRIGERANT SYSTEM
This step covers the refrigerant system of the 604B, including the
compressor oil needed, servicing systems on roofs containing
synthetic materials, the filter drier and refrigerant charging.
A. Refrigerant
CAUTION: This system uses Puron (R-410A) refriger-
ant 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.
B. 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.
C. Servicing Systems on Roofs with Synthetic Materi-
als
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 approxi-
mate 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.
D. 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.
E. 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.
XIV. SYSTEM INFORMATION
A. 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.
B. 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.
Fig. 30—Defrost Thermostat
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.
NOTE: The defrost thermostat must be located on the liquid side
of the outdoor coil on the bottom circuit and as close to the coil as
possible.
TROUBLESHOOTING
Refer to the Cooling and Heating Troubleshooting Chart (Table 7)
for troubleshooting information.
C99029
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