Carrier 30HK - Manual (Page 8)

6. Check leaving chilled water temperature to see
that it remains well above freezing.
7. Recheck compressor oil level. See Check Oil
Charge.
Check Refrigerant Feed Components
THERMOSTATIC EXPANSION VALVE (TXV)
This valve controls refrigerant flow. Valve is
activated by a temperature sensing bulb clamped to
suction line. The valve is factory set to maintain a
superheat of 8 F to 10 F. Do not change setting
unless absolutely necessary.
FILTER DRIER
The 30HK,HL015 thru 030 units (single com­
pressor) have sealed-type driers. When a drier must
be changed, the entire drier must be replaced. The
function of the filter drier is to maintain a clean,
dry system. The moisture indicator (below) can indi­
cate any need to change filter drier.
MOISTURE-LIQUID INDICATOR
The indicator is located immediately ahead of
the TXV to provide a constant indication of refrig­
erant moisture content. It also provides a sight
glass for refrigerant liquid. Clear flow of liquid
refrigerant indicates sufficient charge in system.
Bubbles indicate under-charged system or presence
of noncondensables. Moisture in the system,
measured in parts per million (ppm), will change
color of indicator.
Unit must be in operation at least 12 hours
before moisture indicator will give an accurate
reading. With unit running, indicating element must
be in contact with liquid refrigerant to give true
moisture indication.
At first sign of moisture in the system, change
the filter drier. The tables below indicate when the
change is required.
30HK,HL01 5,020
COLOR CONDITION
Green Dry; moisture is below 45 ppm
Chartreuse Caution: 45 ppm
Yellow Wet; above 130 ppm
30HK,HL025,030
COLOR CONDITION
Blue Safe, dry
Light violet First sign of moisture
Pink Dangerous moisture level
LIQUID-LINE SERVICE VALVE
This valve provides a refrigerant charging port
and, in combination with the compressor discharge
service valve, allows the refrigerant to be pumped
into the high side.
LIQUID-LINE SOLENOID VALVE (HL only)
The solenoid valve closes when its circuit is in­
operative, either from capacity control or from any
safety trip.
PRESSURE RELIEF DEVICES
On HK units, a high-side pressure-relief valve is
factory installed on the condenser. The valve is set
to open at a maximum pressure of 385 psig (maxi­
mum design working pressure of the condenser).
For ЗОНЕ units, pressure relief device, designed
to relieve at 450 psig, is field supplied and installed
in the discharge line after the muffler according to
ANSI.B9.1 code requirements.
Additional pressure relief valves, properly se­
lected, must be field installed to protect field-
installed high-side equipment as may be required by
applicable codes.
A fusible plug is factory installed on the suction
line for low-side protection. This plug will relieve
on temperature rise to 170 F.
Most local codes require that a relief valve be
vented directly to outdoors. The vent line must not
he smaller than the relief valve outlet (518-in. SAE).
CHECK VALVE
A discharge-line check valve is supplied with each
condenseriess (HL) unit as standard equipment.
This valve should be located downstream from, but
close to, the hot gas muffler. The valve can be
mounted in either horizontal or vertical position.
The valve prevents migration of refrigerant from
condenser to compressor and cooler during off-
cycle of compressor.
Check Compressor Protection Devices
CIRCUIT BREAKER
The compressor is protected against an over­
current condition by a manual-reset calibrated-trip
circuit breaker.
IMPOR LAN I l'>o not bypass connections or
increase brcakci si/c ti> correct trouble. Deter­
mine the cause and correct before resetting
breaker.
MOTOR OVERTEMPERATURE
THERMOSTAT
On size 015 units, a sensor embedded in motor
windings protects against overtemperature.
On all other sizes, a sensor in the discharge side
of the compressor reacts to excessively high dis­
charge gas temperature and shuts off the com­
pressor. A high discharge gas temperature indicates
an overtemperature condition in motor windings.
CRANKCASE HEATER
The heater prevents absorption of liquid refrig­
erant by oil when compressor is not operating.
On size 015 units, the heater is secured by a clip;
on all other sizes, it is held in place by a bracket.
t. AU l ION; The hcatci must be light to prevent
il from backing out ot the crankcase. I he heater
will burn out if exposed to aii for an extended
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