Sharp AF-S100RX, Service Manual

Page: 16 / 62

Section 3 Troubleshooting and Testing
3 -1
AIR CONDITIONER VOLTAGE LIMITS
Low voltage is a common cause of trouble in the opera-
tion of any room air conditioner. Improper voltage may
cause one or more of the following problems:
1. Unit will not start.
2. Compressor motor cycling on motor protector.
3. Premature failure of motor protector.
4. Blown fuses.
5. Premature failure of compressor or fan motor.
6. Noticeable dimming of lights when air conditioner is
running.
7. Evaporator icing. Low voltage may reduce fan speed
resulting in inadequate air flow over evaporator,
thereby allowing it to ice up.
Low voltage can also be the direct result of inadequately
wired circuits, extension cords, or loose fuses and
connections to the power supply. Voltage may also be a
general condition in the area (a responsibility of the
power company).
All units will start and run on the minimum voltage
stated in the chart to the left (Figure
4 -1), and will
perform satisfactorily if the voltage remains constant.
Low voltage caused by defective wiring will not remain
constant under load.
To test for low voltage, use a reliable meter with
sufficient capacity to measure the required voltage. Take
measurements at the electric power entry point and at
the electric outlet serving the air conditioner. Take
readings with the unit off, while the unit is starting, and
again while the unit is running. The lowest reading
should not drop below the lowest value listed in the
chart.
HIGH VOLTAGE
High voltage can be equally troublesome, causing motors
to overheat, cycle on their protectors, or break down
electrically. This problem can only be solved by the
power company.
ELECTRONIC CONTROL
This control is not repairable. If any component in the
control is defective, the entire control must be replaced.
Repair or replace any malfunctioning line
voltage component before testing or replacing
the electronic control. DO NOT assume a service
problem is directly caused by the electronic
control system. A line voltage component
(including power cord and wiring) that has
opened, shorted, grounded or otherwise
malfunctioned, may have created a service
problem.
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Figure 3 -1.