Locked Rotor Voltage (L.R.V.) Test
Locked rotor voltage (L.R.V.) is the actual voltage available
at the compressor under a stalled condition.
Single Phase Connections
Disconnect power from unit. Using a voltmeter, attach one
lead of the meter to the run “R” terminal on the compressor
and the other lead to the common “C” terminal of the com
-
pressor. Restore power to unit.
Determine L.R.V.
Start the compressor with the volt meter attached; then stop
the unit. Attempt to restart the compressor within a couple
of seconds and immediately read the voltage on the meter.
The compressor under these conditions will not start and will
usually kick out on overload within a few seconds since the
pressures in the system will not have had time to equalize.
Voltage should be at or above minimum voltage of 197 VAC,
as specified on the rating plate. If less than minimum, check
for cause of inadequate power supply; i.e., incorrect wire
size, loose electrical connections, etc.
ELECTRIC SHOCK HAZARD
WARNING
Turn off electric power before service or
installation. Extreme care must be used, if it
becomes necessary to work on equipment with
power applied.
Failure to do so could result in serious injury or
death.
COMPReSSOR CHeCKS
Amperage (L.R.A.) Test
The running amperage of the compressor is the most impor-
tant of these readings. A running amperage higher than that
indicated in the performance data indicates that a problem
exists mechanically or electrically.
Single Phase Running and L.R.A. Test
NOTE:
Consult the specification and performance section
for running amperage. The L.R.A. can also be found on the
rating plate.
Select the proper amperage scale and clamp the meter
probe around the wire to the “C” terminal of the compressor.
Turn on the unit and read the running amperage on the me-
ter. If the compressor does not start, the reading will indicate
the locked rotor amperage (L.R.A.).
ELECTRIC SHOCK HAZARD
WARNING
Turn off electric power before service or
installation. Extreme care must be used, if it
becomes necessary to work on equipment with
power applied.
Failure to do so could result in serious injury or
death.
18
1. With no power to unit, remove the leads from the com-
pressor terminals.
2. Using an ohmmeter, test continuity between terminals
C-S and C-R. If no continuity, the compressor overload
is open and the compressor must be replaced.
CHECKING THE INTERNAL OVERLOAD
INTERNAL OVERLOAD
Should the internal temperature and/or current draw become
excessive, the contacts in the overload will open, turning off
the compressor. The overload will automatically reset, but
may require several hours before the heat is dissipated.
Internal Overload
ELECTRIC SHOCK HAZARD
WARNING
Disconnect power to the unit before
servicing. Failure to follow this warning
could result in serious injury or death.
The compressors are equipped with an internal overload.
The overload is embedded in the motor windings to sense
the winding temperature and/or current draw. The overload
is connected in series with the common motor terminal
