Carrier Acqua Junior 30AJ Series Installation, Operation And Maintenance Manual page 70

8. Maintenance
8.1 Electric box
a) General notes :
The electric box of the 30AJ units were designed in order
to make the inspection and maintenance services easier.
All the control, start-up and protection devices are located
there. Exist two terminals block to control and power wire.
In the terminal block also be includ the ground terminal.
b) Pressure switch:
The pressure switch in the machines 30AJ are the individual
type both sides(High and Low). Both are rearm automatic
and of the side high it the type miniature connected in the
discharge line. Independent of it rearms to be automatic
or manual when disarming the machine is blocked for the
module. The valves of disarm these pressure switch are
indicated in the table of general characteristics.
8.2 Eventual failures
Problem
1. Unit does not start up.
2. Condenser fan does not run.
3. Compressor ''roars" but does not
start up.
4. Compressor starts up, but does not
run continuously.
70
Probable Cause
Phases R, S, T are not in the correct sequence.
Lack of power supply.
Inadequate voltage or out of the allowed limits.
Burnt control fuses.
Protection devices opened.
Faulty contactor, motor or compressor.
Defective overload relay or contactor.
Defective motor.
Bad contact in the electrical connections.
Low voltage.
Faulty compressor motor.
"Locked" compressor.
Defective compressor or contactors.
Lack of refrigerant
Insuffi cient thermal load.
Compressor motor overload or overheating.
A time verifi ed and cured the cause of disarms it, reseting
can to be made disconnect and restarting the unit in the
panel of control or through the restoration of power to
the command.
d) Protection of the compressors:
- Compressors 220 and 380V - Line break (intern)
The "line break" is a protection dispositive against overload
and superheating of the engine from the compressor that
is installed inside (in the stator of motor). It directly acts in
the circuit of engine force, rearming automatically with the
decrease of the temperature, however the compressor will
remain off due action of the device anti-recycle. It rearms it
can be made through the key ON/OFF from the unit.
Procedure
• Revert the power supply
cables in the connection.
• Check power supply.
• Check fuses, circuit
breakers and switches.
• Check electrical contacts.
• Check and correct.
• Check control short circuit,
wrong connection or faulty
items. Fix and replace fuses.
• Check pressostats, fl ow switches,
relays and auxiliary contacts.
• Test and replace.
• Test and replace.
• Test and replace.
• Check and tighten.
• Check and tighten.
• Replace compressor.
• Check and replace compressor.
• Test and replace.
• Check and correct loss.
• Add refrigerant if necessary.
• Check design conditions.
• Check protection device
operation. Replace if necessary.
• Check voltage or phase
imbalance. Correct the problem.
• Check expansion
valve adjustments.
• Check temperature (or pressure)
at suction and at condensation.