Carrier 19CB - Manual (Page 8)

knob on demand limit control at 100% and turn
calibration screw fully clockwise.
Place a clamp-on ammeter on one of the 3
starter leads. Be sure ammeter scale is set so that
compressor full load amperage will register be­
tween midway and just under the top of the scale.
Install jumpers between ^ and [^, and
between and 11 Close disconnects, start
compressor and check oil pressure and temperature
(Fig. 2). With compressor running, operate the
guide vanes with capacity control switch or pneu­
matic thermostat. Do not exceed 100% full load
amps.
1. Check controls 1 and 2 as indicated in Table 4.
2. Stop machine, open disconnects, remove
jumpers and check controls 3, 4 and 5 as
indicated.
Table 4 — Setting Safety Controls
SAFETY OR CONTROL DEVICE
1. Chilled Water Low-Temperature Cutout and Recycle Switch
(Fig. 1)
'TEMPERATURE AD.IUSTMENl
^ O,
DIFFERENTIAL ADJUSTMENT
JZ, —’ ''Bi*
Set this switch to break at approximately 5 F below design
chilled water temperature, or at 36 F whichever is higher
Set the differential at 10 ± 1 F so that when the machine shuts
down automatically at approximately 5 F below the design
chilled water temperature it will restart at approximately 5 F
above the design water temperature.
This control must break ahead of the refrigerant low-
temperature cutout switch or the machine will not recycle
automatically
2. Refrigerant Low-Temperature Cutout (Fig. 6)
CUTOUT
ADJUSTMENT
Set refrigerant low-temperature cutout at 33 F or one degree below
design refrigerant temperature, whichever is lower, while checking
temperature at thermowell near control center
SAFETY OR CONTROL DEVICE
STOP MACHINE, REMOVE JUMPERS AND PEREORM RE­
MAINING CHECKS.
3. Condenser High-Pressure Cutout (Fig. 6)
CUTOUT ADJUSTMENT .f.'
COVER
JiEFRlG
ii
114
SETTING
15 psig
45 psig
RESET
BUTTON
CUTOUT SCALE
The condenser high-pressute cutout is factory set to shut the
machine down when condenser pressure reaches setting listed.
Isolate the switch and check setting with a metered supply of air
4. Oil Heater Thermostat (Fig. 2)
Set the oil heater thermostat to maintain a minimum oil reservoir
temperature of 140 F at shutdown.