SERVICING
26
S-8 CHECKING CONTACTOR CONTACTS
WARNING
DISCONNECT POWER SUPPLY BEFORE SERVICING.
SINGLE PHASE
1. Disconnect the wire leads from the terminal (T) side of the
contactor.
2. With power ON, energize the contactor.
WARNING
LINE VOLTAGE NOW PRESENT.
VOLT/OHM
METER
T1
T2
L1
L2
CC
Ohmmeter for testing holding coil
Voltmeter for testing contacts
TESTING COMPRESSOR CONTACTOR
(Single Phase)
3. Using a voltmeter, test across terminals.
A.
L1 to L2 - No voltage. Check breaker or fuses on main
power supply. If voltage present, proceed to step B.
B.
T1 to T2 - Meter should read the same as L1 to L2 in
step A. If voltage readings are not the same as step A,
replace contactor.
S-11 CHECKING LOSS OF CHARGE
PROTECTOR
(Heat Pump Models)
The loss of charge protector senses the pressure in the liquid
line and will open its contacts on a drop in pressure. The low
pressure control will automatically reset itself with a rise in
pressure.
The low pressure control is designed to cut-out (open) at ap-
proximately 22 + 7 PSIG. It will automatically cut-in (close) at
approximately 50 + 7 PSIG.
Test for continuity using a VOM and if not as above, replace
the control.
S-12 CHECKING HIGH PRESSURE CONTROL
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing this unit. Multiple power
sources may be present. Failure to do so
may cause property damage, personal injury
or death.
The high pressure control senses the pressure in the liquid
line. If abnormally high discharge pressures develop, the con-
tacts of the control open, breaking the control circuit before the
compressor motor overloads. This control is automatically re-
set.
1. Using an ohmmeter, check across terminals of high pres-
sure control, with wire removed. If not continuous, the con-
tacts are open.
2. Attach a gauge to the access fitting on the liquid line.
With power ON:
WARNING
LINE VOLTAGE NOW PRESENT.
3. Start the system and place a piece of cardboard in front of
the condenser coil, raising the condensing pressure.
4. Check pressure at which the high pressure control cuts-
out.
If it cuts-out at 610 PSIG ± 10 PSIG, it is operating normally
(See causes for high head pressure in Service Problem Analy-
sis Guide). If it cuts out below this pressure range, replace the
control. The control should reset at 420 PSIG ± 25 PSIG.
S-15 CHECKING CAPACITOR
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.
