34
CAPACITORS
ELECTRIC SHOCK HAZARD
WARNING
Turn off electric power before servicing.
Discharge capacitor with a 20,000 Ohm 2 Watt
resistor before handling.
Failure to do so may result in personal injury,
or death.
Many motor capacitors are internally fused. Shorting the
terminals will blow the fuse, ruining the capacitor. A 20,000
ohm 2 watt resistor can be used to discharge capacitors
safely. Remove wires from capacitor and place resistor
across terminals. When checking a dual capacitor with
a capacitor analyzer or ohmmeter, both sides must be
tested.
Capacitor Check with Capacitor Analyzer
The capacitor analyzer will show whether the capacitor is
“open” or “shorted.” It will tell whether the capacitor is within
its micro farads rating and it will show whether the capacitor
is operating at the proper power-factor percentage. The
instrument will automatically discharge the capacitor when
the test switch is released.
Capacitor Connections
The starting winding of a motor can be damaged by a
shorted and grounded running capacitor. This damage
usually can be avoided by proper connection of the running
capacitor terminals.
From the supply line on a typical 230 volt circuit, a 115 volt
potential exists from the “R” terminal to ground through a
possible short in the capacitor. However, from the “S” or
start terminal, a much higher potential, possibly as high as
400 volts, exists because of the counter EMF generated
in the start winding. Therefore, the possibility of capacitor
failure is much greater when the identi
fi
ed terminal is
connected to the “S” or start terminal. The identi
fi
ed
terminal should always be connected to the supply line, or
“R” terminal, never to the “S” terminal.
When connected properly, a shorted or grounded running
capacitor will result in a direct short to ground from the “R”
terminal and will blow the line fuse. The motor protector
will protect the main winding from excessive temperature.
Dual Rated Run Capacitor Hook-up
BLOWER/FAN MOTOR - TEST
1. Determine that capacitor is serviceable.
2. Disconnect fan motor wires from fan speed switch or
system switch.
3. Apply “live” test cord probes on black wire and common
terminal of capacitor. Motor should run at high speed.
4. Apply “live” test cord probes on red wire and common
terminal of capacitor. Motor should run at low speed.
5. Apply “live” test cord probes on each of the remaining
wires from the speed switch or system switch to test
intermediate speeds. If the control is in the “MoneySaver”
mode and the thermostat calls for cooling, the fan will
start - then stop after approximately 2 minutes; then the
fan and compressor will start together approximately 2
minutes later.
Figure 23
Blower/Fan Motor
FAN MOTOR
A single phase permanent split capacitor motor is used to drive
the evaporator blower and condenser fan. A self-resetting
overload is located inside the motor to protect against high
temperature and high amperage conditions. (See Figure 23)
ELECTRIC SHOCK HAZARD
WARNING
Disconnect power to the unit before
servicing. Failure to follow this warning
could result in serious injury or death.
COMPONENTS TESTING
