Service Manual
SERVICING
26
M ODELS EQUIPPED W ITH A HARD START DEVICE
A st art capacitor is wired in parallel with the run capacit or to
increase t he st art ing torque. The start capacitor is of the elec-
trolytic t ype, rat her than metallized polypropylene as used in
the run capacitor.
A sw itching device must be wired in series with the capacitor to
remove it from the elect rical circuit aft er the compressor st arts
to run. Not removing the st art capacit or will overheat the ca-
pacit or and burn out the compressor windings.
These capacitors have a 15,000 ohm, 2 wat t resistor wired across
its terminals. The object of the resist or is to discharge t he ca-
pacit or under cert ain operat ing conditions, rat her than having it
discharge across the closing of the contacts within the sw itching
device such as the St art Relay, and to reduce t he chance of shock
to t he servicer. See the Servicing Section for specific informat ion
concerning capacitors.
RELAY, START
A potential or voltage type relay is used to t ake the st art capaci-
tor out of the circuit once the motor comes up to speed. This
type of relay is posit ion sensitive. The normally closed contact s
are w ired in series wit h the start capacitor and the relay holding
coil is wired parallel wit h the st art winding. As the mot or start s
and comes up to speed, the increase in volt age across the start
winding w ill energize the start relay holding coil and open t he
contacts to the start capacit or.
Two quick ways to test a capacitor are a resist ance and a capaci-
tance check.
S-15A RESISTANCE CHECK
WARNING
1. Discharge capacit or and remove wire leads.
WARNING
DISCHARGE CAPACITOR THROUGH A 20 TO 30 OHM
RESISTOR BEFORE HANDLING.
Capacit
o
r
Volt / Ohm
Meter
TESTING CAPACITOR RESISTANCE
2. Set an ohmmet er on it s highest ohm scale and connect the
leads to the capacit or -
A. Good Condition - indicat or swings to zero and slowly re-
turns to infinity. (Start capacit or will bleed resistor will not
return to infinity. It will still read the resistance of the resis-
tor).
B. Short ed - indicator swings to zero and st ops there - re-
place.
C. Open - no reading - replace. (Start capacitor would read
resist or resist ance).
S-15B CAPACITANCE CHECK
WARNING
DISCHARGE CAPACITOR THROUGH A 20 TO 30 OHM
RESISTOR BEFORE HANDLING.
Using a hookup as shown below , take the amperage and volt age
readings and use them in t he formula:
Capacitance (M FD) =
2650 X Amperage
Voltage