Table of Contents
Advertisement
n
If oil is detected
or if low performance
is suspected,
leak test all
refrigerant
tubing using an electronic
leak detector,
or liquid-soap
solution.
If a refrigerant
leak
is detected,
refer
to Check
for
Refrigerant
Leaks section.
If no refrigerant
leaks are found and low performance
is suspected,
refer to Checking
and Adjusting
Refrigerant
Charge section.
Step 7--Indoor
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.
Step 8--Metering
Devices-TXV
This
unit uses
a TXV-type
metering
device.
No maintenance
should be required.
Step 9--Pressure
Switches
Pressure switches
are protective devices
integrated into the 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
nmst not be used as
replacements
for the Puron (R-410A)
system.
Loss-of-Char_,e
(Low Pressure)
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, dirt}, filters, etc. It opens
if the system
pressure
drops to about
20 psig. If system
pressure
is above this.
switch should be closed.
Hi_,h-Pressure
Switches
(HPS & HPS2)
The high-pressure
switches
are located
on the discharge
line and
protects
against
excessive
condenser
coil pressure.
HPS opens
at
670 psig shutting
down the compressor,
while HPS2 opens at 565.
limiting
the compressor
to low-stage
operation
only.
High pressure
may be caused
by a dirty outdoor
coil. failed
fan
motor, or outdoor
air recirculation.
To check switches:
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 10--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.
EXPLOSION,
FIRE
HAZARD
Failure to follow this warning
could result in personal
injury
or death and/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
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 conlpressor
uses Mobil
3MA POE oil. This
is the only oil allowed
for oil recharge.
Step ll--Refrigerant
System
This step covers the refrigerant
system of the 50DU,
including
the
compressor
oil needed,
servicing
systems
on roofs
containing
synthetic
materials,
the filter drier, and refrigerant
charging.
REFRIGERANT
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 vou are unsure, consult
the equipment
manufacturer.
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
inmmdiately
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, and replacing
refrigerant
components
such
as filter
drier,
pressure
switch.
metering
device,
coil. accumulator,
or reversing
valve.
Synthetic
Roof Precautionary
Procedure
1. (;over
extended
roof working
area with
an impermeable
polyethylene
(plastic)
drip
cloth
or
tarp.
(:over
an
approximate
10 X 10 ft area.
2. (;over 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.
22
Advertisement
Table of Contents
