Carrier 07KA - Manual (Page 2)

COMPRESSOR
When supply voltage is within 10% limit and
compressor does not start, give compressor a
temporary capacitance boost. Use a start booster
assembly.
Run compressor for 10 minutes, then shut off
and allow system pressure to equalize. Try re­
starting without boost capacitor. If after two at-
temps
the compressor does not start, add an
accessory start capacitor relay package.
The accessory start relay used with the 06A
compressor has a current-limiting device to pro­
tect the compressor in case of relay malfunction.
An
open current-limiting device indicates that
the relay must be changed.
Compressor Protection - 07KA units have a high
pressurestat located on liquid service valve and
a
low pressurestat located on suction service
valve. (See Table 1 for high and low pressure­
stat settings.)
Single-phase compressor motors are protected
by an internal current temperature-sensitive
overload. Three-phase compressors are pro­
tected by internal thermostat and external current
overloads.
Internal temperature-sensitive over­
loads reset automatically when internal motor
temperatures drop to a safe level. (Overloads
may require up to 30 minutes to reset.)
When an internal overload is suspected of
being open, check by using an ohmmeter or con­
tinuity tester. Refer to the Carrier Standard Serv­
ice Techniques Manual, Chapter 2 for complete
instructions.
Compressor Removal
1. Shut off power to unit. Vent refrigerant to at­
mosphere or use refrigerant removal methods
described in Carrier Standard Service Tech­
niques Manual, Chapter 1.
2. Remove both unit top cover and wrap-around
enclosure.
3. Remove compressor power leads from unit
control box and pressure relief plug from suc­
tion line. Unsweat suction and hot gas lines
from compressor.
4. Remove compressor hold-down bolts. Lift
compressor out thru top of unit.
REFRIGERANT CHARGING
07KA units contain correct operating charge
(Table 1) for complete system when combined
with
Carrier approved capillary-controlled evap­
orator sections and with a Carrier accessory
precharged tubing package in 10- or 18-ft lengths.
Additional charge may be required on other sys­
tems. Add a crankcase heater to 07KA002 when
factory
charge is exceeded. (Crankcase heater
available from Carrier Service Parts Center,
part no. HT32AZ242.) Do not use condensing unit
charge for purging evaporator or tubing systems.
Refer to Carrier Standard Service Techniques
Manual, Chapter 1 for system evacuation, de­
hydration instructions and details of charging
methods listed below.
Service valve access cover is provided to
accommodate charging lines. Replace cover when
finished.
Weight Method - Systems with capillary tube con­
trol are recharged by weight only. Refer to Table
1 for correct system charge. Blow any refrig­
erant remaining in system before recharging.
When interconnecting tubing is shorter than
10 ft or longer than 18 ft, add (subtract) charge
as follows:
3/4 oz per 10 ft of 5/16-in. OD liquid line.
1-1/2 oz per 10 ft of 3/8-in. OD liquid line.
Sight Glass Method - A satisfactory operating
charge for thermal expansion valve controlled
systems can be obtained by weighing in the refrig-
erant charge shown in Table 1 for capillary feed
coil systems. Then, if liquid line sight glass is not
clear, add refrigerant until sight glass clears at
an operating condition of between 110 F and 120 F
condensing temperature.
For maximum capacity (with thermal expansion
valve systems), slightly more charge is required
than will be provided by the above procedure. To
achieve this optimum charge, proceed as follows:
1. Charge per above.
2. Holding pressure at liquid valve {hy hand throt-
tling the condenser water) to a corresponding
saturation temperature of approximately 115 F,
add refrigerant charge until actual liquid tem­
perature at this point is approximately 97 F
(18 F liquid subcooling).
3. In any case, do not charge system to more than
3 lb for systems with 002 and 003 size coils and
4 lb for systems with 004 and 005 size coils.
CHECKING COMPONENTS
Refer to Carrier Standard Service Techniques
Manual, Chapter 2 for complete instructions on
checking electrical components.
PUMPDOWN PROCEDURE
07KA units may be pumped down in order to
make repairs on low side of system without losing
complete refrigerant charge.
1. Attach pressure gage to suction service valve
gage port.
2. Front-seat liquid line valve.
3. Jumper low pressure switch.
4. Start unit and run until the suction pressure
reaches 5 psig. (Should the compressor go off
on internal overload or high pressurestat be­
fore suction pressure reaches 5 psig, shut off
suction valve and vent remaining refrigerant.)