SERVICING
184 Rev. 3
This check valve closes off high side pressure to the com-
pressor after shut down allowing equalization through the scroll
flanks. Equalization requires only about one or two seconds
during which time the compressor may turn backwards (K1
& K2 model scrolls).
To prevent the compressor from starting and running back-
wards a Time Delay Relay (Cycle Protector) has been added
to the low voltage circuit. K3 model scroll compressors equal-
ize in less than one second after shut down and do not re-
quire a Time Delay Relay (Cycle Protector) for proper opera-
tion.
ALL OTHER MODELS
CAPACITOR, RUN
A run capacitor is wired across the auxiliary and main wind-
ings of a single phase permanent split capacitor motor. The
capacitors primary function is to reduce the line current while
greatly improving the torque characteristics of a motor. This
is accomplished by using the 90° phase relationship between
the capacitor current and voltage in conjunction with the motor
windings so that the motor will give two phase operation when
connected to a single phase circuit. The capacitor also re-
duces the line current to the motor by improving the power
factor.
The line side of this capacitor is marked with a red dot and is
wired to the line side of the circuit.
CAPACITOR, START
A start capacitor is wired in parallel with the run capacitor to
increase the starting torque. The start capacitor is of the
electrolytic type, rather than metallized polypropylene as used
in the run capacitor.
A switching device must be wired in series with the capacitor
to remove it from the electrical circuit after the compressor
starts to run. Not removing the start capacitor will overheat
the capacitor and burn out the compressor windings.
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.
START
RELAY
CO
M
HE
R
M
FA
N
RUN
CAPACITOR
CONTACTOR
T2 T1
L1
L2
START
CAPACITOR
RED 10
VIOLET 20
YELLOW 12
ORANGE 5
Two quick ways to test a capacitor are a resistance and a
capacitance check.
S-15A Resistance Check
WARNING
Disconnect Electrical Power Supply:
1. Discharge capacitor and remove wire leads.
WARNING
DISCHARGE CAPACITOR THROUGH A 20 TO 30 OHM
RESISTER 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 will 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).
