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Testing Procedures
To avoid risk of electrical shock, personal injury, or death, disconnect electrical power source to unit and
discharge capacitor through a 10,000 ohm resistor before attempting to service, unless test procedures require
power to be connected. Ensure all ground wires are connected before certifying unit as repaired and/or
operational.
Low Voltage
Low voltage can result in one or more of the following
problems:
· Unit will not operate.
· Compressor motor cycling.
· Premature failure of overload protector.
· Frequent blown fuses or tripped circuit breakers.
· Premature failure of compressor or fan motor.
· Noticeable dimming of lights when unit is operating.
· Evaporator icing, caused by reduced fan speed.
Common causes for low voltage include inadequate
supply circuit wiring; use of extension cords; and loose
fuses or connections in fuse box, circuit breaker, or
distribution panel.
NOTE: A good indication of voltage problems caused by
inadequate or faulty wiring is voltage levels that
do not remain constant under load (supply
voltage fluctuates).
A less common cause for low voltage is voltage from
local electric utility is low (sometimes called "brown
outs"). If this is the case, have consumer contact local
electric utility for assistance.
All units should operate normally if power stays within
specifications (refer to Technical Sheet for unit under
test).
Test for low voltage using voltmeter. Verify voltage level
at circuit breaker/distribution panel for unit under test,
and at electrical outlet serving unit. Take initial voltage
readings with air conditioner turned off. Take additional
readings during start-up of unit, and again while unit is
operating. All readings should be within specifications
and remain constant.
NOTE: Supply voltage may drop momentarily during
initial start-up and when compressor first starts,
but should always remain within specifications.
High Voltage
High voltage causes motors to overheat, cycle on their
protectors, or break down electrically. This problem can
only be solved by local electric utility.
RS4100004 Rev. 0
!
WARNING
Electronic Control
Electronic control is not repairable. If any component in
control is faulty, entire control must be replaced.
NOTE: Repair or replace all faulty line voltage
components before testing or replacing
electronic control. Do not assume problems are
caused by electronic control system. Opened,
shorted, grounded or otherwise faulty line
voltage components (including power cord and
building wiring) can create problems that appear
to be caused by electronic control.
Testing Capacitors
Compressors in these units use permanent split
capacitor type motors, eliminating need for start
capacitors and relays. A low capacitance "compressor
run capacitor" assists during start, and remains in
system during operation. Line side of run capacitor is
marked with a dot and must be installed on line side of
supply circuit. See directions on capacitor, and wiring
diagram (on Technical Sheet) for unit under test.
Capacitors are also used on permanent split capacitor
(PSC) fan motors.
To test capacitors:
1. Disconnect power to unit.
2. Discharge capacitor by shorting capacitor terminals
through a 10,000 ohm resistor. Disconnect leads
attached to capacitor terminals.
3. Set ohmmeter on highest scale. Attach ohmmeter
leads to capacitor and observe ohmmeter display:
· Good condition—indicator swings to zero and
slowly returns toward infinity.
· Shorted—indicator swings to zero and remains.
Replace capacitor.
· Open—indicator does not move. Replace capacitor.
4. Reverse ohmmeter leads on capacitor and repeat
step 3.
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