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SERVICING
42
The discharge check valve closes off high side pressure to the
compressor after shut down allowing equalization through the
scroll flanks. Equalization requires only about ½ second.
To prevent the compressor from short cycling, a Time Delay
Relay (Cycle Protector) has been added to the low voltage
circuit.
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.
START
RELAY
C
O
M
H
E
R
M
F
A
N
RUN
CAPACITOR
CONTACTOR
T2 T1
L1L2
START
CAPACITOR
RED 10
VIOLET 20
YELLOW 12
ORANGE 5
HARD START KIT WIRING
S-15A RESISTANCE CHECK
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing. Multiple power sources
may be present. Failure to do so may
cause property damage, personal injury
or death.
1. Discharge capacitor and remove wire leads.
WARNING
Discharge capacitor through a 20 to 30 OHM
resistor before handling.
OHMMETER
CAPACITOR
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:
VOLTMETER
CAPACITOR
AMMETER
15 AMP
FUSE
TESTING CAPACITANCE
WARNING
Discharge capacitor through a 20 to 30 OHM
resistor before handling.
Capacitance (MFD) = 2650 X Amperage
Voltage