SERVICING
38
These capacitors have a 15,000 ohm, 2 watt resistor wired
across its terminals. The object of the resistor is to dis-
charge the capacitor under certain operating conditions, rather
than having it discharge across the closing of the contacts
within the switching device such as the Start Relay, and to
reduce the chance of shock to the servicer. See the Servic-
ing Section for specific information concerning capacitors.
RELAY, START
A potential or voltage type relay is used to take the start
capacitor out of the circuit once the motor comes up to speed.
This type of relay is position sensitive. The normally closed
contacts are wired in series with the start capacitor and the
relay holding coil is wired parallel with the start winding. As
the motor starts and comes up to speed, the increase in
voltage across the start winding will energize the start relay
holding coil and open the contacts to the start capacitor.
Two quick ways to test a capacitor are a resistance and a
capacitance check.
S-15A Resistance Check
WARNING
HIGH
VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
INSTALLING THIS UNIT.
M
ULTIPLE POWER SOURCES MAY
BE PRESENT.
F
AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1. Discharge capacitor and remove wire leads.
Ca
pa
cit
or
Volt / Ohm
Meter
TESTING CAPACITOR RESISTANCE
2. Set an ohmmeter on its highest ohm scale and connect
the leads to the capacitor -
A. Good Condition - indicator swings to zero and slowly
returns to infinity. (Start capacitor with bleed resistor will
not return to infinity. It will still read the resistance of the
resistor).
B. Shorted - indicator swings to zero and stops there -
replace.
C. Open - no reading - replace. (Start capacitor would
read resistor resistance).
S-15B Capacitance Check
Using a hookup as shown below, take the amperage and
voltage readings and use them in the formula:
Capacitance (MFD) = 2650 X Amperage
Voltage
15 AMP FUSE
Volt / Ohm
Meter
AMMETER
Ca
pa
ci
tor
TESTING CAPACITANCE
S-16 CHECKING FAN AND BLOWER MOTOR
An auto reset fan motor overload is designed to protect the
motor against high temperature and high amperage condi-
tions similar to the compressor internal overload. It also breaks
the common circuit within the motor shell; however, heat gen-
erated within the motor is faster to dissipate than the com-
pressor, allow at least 45 minutes for the overload to reset,
then retest.
WARNING
D
ISCONNECT ELECTRICAL POWER SUPPLY.
1. Remove the motor leads from its respective connection
points and capacitor (if applicable).
2. Check the continuity between each of the motor leads.
3. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.
If the windings do not test continuous or a reading is ob-
tained from lead to ground, replace the motor.