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If no refrigerant leaks are found and low cooling performance is
suspected, refer to the Checking and Adjusting Refrigerant
Charge section.
GAS INPUT
The gas input does not require checking unless improper heating
performance is suspected. If a problem exists, refer to the
Start- -Up section.
EVAPORATOR AIRFLOW
The heating and/or cooling airflow does not require checking
unless improper performance is suspected. If a problem exists, be
sure that all supply- - and return- -air grilles are open and free from
obstructions, and that the air filter is clean. When necessary, refer
to the Indoor Airflow and Airflow Adjustments section to check
the system airflow.
PURON ITEMS
METERING DEVICE - - Thermostatic Expansion Valve This
metering device is a hard shutoff, balance port TXV. The TXV
maintains a constant superheat at the evaporator exit resulting in
higher overall system efficiency.
PRESSURE SWITCHES
Pressure switches are protective devices wired into control circuit
(low voltage). They shut off compressor if abnormally high or
low pressures are present in the refrigeration circuit. These
pressure switches are specifically designed to operate with Puron
(R- -410A) systems. R- -22 pressure switches must not be used as
replacements for the Puron (R- -410A) system.
LOSS OF CHARGE SWITCH
This switch is located on the liquid line and protects against low
suction pressures caused by such events as loss of charge, low
airflow across indoor coil, dirty filters, etc. It opens on a pressure
drop at about 20 psig. If system pressure is above this, switch
should be closed. 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.
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.
HIGH- -PRESSURE SWITCH
The high- -pressure switch is located in the discharge line and
protects against excessive condenser coil pressure. It opens at 610
psig.
High pressure may be caused by a dirty outdoor coil, failed fan
motor, or outdoor air recirculation. 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.
COPELAND SCROLL COMPRESSOR (PURON
REFRIGERANT)
The compressor used in this product is specifically designed to
operate with Puron (R- -410A) refrigerant and cannot be
interchanged.
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
techniques. Refrigerants present additional safety hazards.
WARNING
!
FIRE/EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death or property damage.
Wear safety glasses and gloves when handling refrigerants.
Keep torches and other ignition sources away from
refrigerants and oils.
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
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.
WARNING
!
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could result in personal injury
or equipment damage.
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.
REFRIGERANT SYSTEM
This information covers the refrigerant system of the 574B,
including the compressor oil needed, servicing systems on roofs
containing synthetic materials, the filter drier and refrigerant
charging.
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-
MATERIALS
POE (polyolester) compressor lubricants are known to cause long
term damage to some synthetic roofing materials.
Exposure, even if immediately cleaned up, may cause
embrittlement (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. Procedures which risk oil leakage include, but are not
limited to, compressor replacement, repairing refrigerant leaks,
replacing refrigerant components such as filter drier, pressure
switch, metering 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
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is
equipped
with
an
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