SERVICING
30
S-17B GROUND TEST
If fuse, circuit breaker, ground fault protective device, etc., has
tripped, this is a strong indication that an electrical problem
exists and must be found and corrected. The circuit protective
device rating must be checked and its maximum rating should
coincide with that marked on the equipment nameplate.
With the terminal protective cover in place, it is acceptable to
replace the fuse or reset the circuit breaker ONE TIME ONLY
to see if it was just a nuisance opening. If it opens again, DO
NOT continue to reset.
Disconnect all power to unit, making sure that all power legs
are open.
1. DO NOT remove protective terminal cover. Disconnect the
three leads going to the compressor terminals at the near-
est point to the compressor.
WARNING
DAMAGE CAN OCCUR TO THE GLASS EMBEDDED
TERMINALS IF THE LEADS ARE NOT PROPERLY
REMOVED. THIS CAN RESULT IN TERMINAL AND
HOT OIL DISCHARGING.
HI-POT
COMPRESSOR GROUND TEST
2. Identify the leads and using a Megger, Hi-Potential Ground
Tester, or other suitable instrument which puts out a volt-
age between 300 and 1500 volts, check for a ground sepa-
rately between each of the three leads and ground (such
as an unpainted tube on the compressor). Do not use a
low voltage output instrument such as a volt-ohmmeter.
3. If a ground is indicated, then carefully remove the compres-
sor terminal protective cover and inspect for loose leads or
insulation breaks in the lead wires.
4. If no visual problems indicated, carefully remove the leads
at the compressor terminals.
Carefully retest for ground, directly between compressor
terminals and ground.
5. If ground is indicated, replace the compressor.
S-17D OPERATION TEST
If the voltage, capacitor, overload and motor winding test fail to
show the cause for failure:
WARNING
1. Remove unit wiring from disconnect switch and wire a test
cord to the disconnect switch.
NOTE:
The wire size of the test cord must equal the line wire
size and the fuse must be of the proper size and type.
2. With the protective terminal cover in place, use the three
leads to the compressor terminals that were disconnected
at the nearest point to the compressor and connect the
common, start and run clips to the respective leads.
3. Connect good capacitors of the right MFD and voltage rat-
ing into the circuit.
4. With power ON, close the switch.
WARNING
LINE VOLTAGE NOW PRESENT.
A.
If the compressor starts and continues to run, the
cause for failure is somewhere else in the system.
B.
If the compressor fails to start - replace.
The condition of the scroll flanks is checked in the following
manner.
1. Attach gauges to the high and low side of the system.
2. Start the system and run a “Cooling Performance Test.
If the test shows:
a. Below normal high side pressure.
b. Above normal low side pressure.
c. Low temperature difference across coil.
d. Low amp draw at compressor.
and the charge is correct, test the reversing valve if equipped
(heat pump models only. See-S-21). If the reversing valves
test good, the compressor is faulty - replace the compressor.
