24
C99097
Fig. 27 -- Refrigerant Circuit
Step 9 — 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.
Step 10 — 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.
Step 11 — 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.
Step 12 — 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.
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 refrigerant
and oils.
!
WARNING
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 3MAF POE oil.
Copeland Ultra 22 CC should be used if additional oil is needed
in the field. Mobil Artic EAL22CC or ICI Emkarate RL22 or
32CF oil may be used to recharge these compressors if Ultra 22
is not available.
Step 13 — Refrigerant System
This step covers the refrigerant system of the 604D, including the
compressor oil needed, servicing systems on roofs containing
synthetic materials, the filter drier and refrigerant charging.
REFRIGERANT
PROPERTY HAZARD OR PERSONAL INJURY
HAZARD
Failure to follow this warning could result in property damage
or personal injury or death.
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.
!
WARNING
COMPRESSOR OIL
The compressor in this system uses a polyolester (POE) oil,
Mobil 3MAF 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
604D
