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DANGER OF BODILY INJURY OR DEATH
FROM ELECTRICAL SHOCK
When working on high voltage equipment - turn the
electrical power off before attaching test leads.
Use test leads with alligator type clips - clip to
ter mi nals, turn power on, take reading - turn pow er
off before removing leads.
COMPRESSOR CHECKS
Locked Rotor Voltage (L.R.V.) Test
Locked rotor voltage (L.R.V.) is the ac tu al 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.
Make sure that the ends of the lead do not touch
the compressor shell since this will cause a short
circuit.
Reversing Valve in Cooling Mode
8. Pressurize sealed system with a combina tion of R-22
and nitrogen and check for leaks, using a suitable leak
detector. Recover refrigerant per EPA guidelines.
9. Once the sealed system is leak free, in stall solenoid coil
on new valve and charge the sealed system by weighing
in the proper amount and type of re frig er ant as shown
on rating plate. Crimp the process tubes and solder the
ends shut. Do not leave Schrader or piercing valves in
the sealed system.
Determine L.R.V.
Start the compressor with the volt me ter attached; then
stop the unit. Attempt to re start the compressor within a
couple of seconds and immediately read the voltage on the
meter. The com pres sor 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 spec i fi ed on the rating plate. If less than
mini mum, check for cause of in ad e quate power supply; i.e.,
incorrect wire size, loose elec tri cal con nec tions, etc.
Amperage (L.R.A.) Test
The running amperage of the com pres sor is the most
important of these read ings. A run ning amperage higher
than that in di cat ed in the performance data indicates that
a prob lem exists mechanically or elec tri cal ly.
Single Phase Running and L.R.A. Test
NOTE: Consult the specifi cation and perform ance section
for running am per age. 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 am perage on the
meter. If the compressor does not start, the reading will
indicate the locked rotor amperage (L.R.A.).
External Overload
The compressor is equipped with an exter nal overload
which senses both motor am per age and winding
temperature. High motor tempera ture or amperage heats
the over load causing it to open, breaking the common
circuit within the compressor.
Heat generated within the com pres sor shell, usually due
to recycling of the motor, is slow to dissipate. It may take
anywhere from a few minutes to several hours for the
over load to re set.
Checking the External Over load
With power off, remove the leads from com pressor
terminals. If the compressor is hot, allow the overload
to cool before start ing check. Using an ohmmeter, test
con ti nu ity across the terminals of the external overload. If
you do not have continuity; this indicates that the over load
is open and must be replaced.
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