SERVICING
11
Ignition of the discharge can also occur at the venting
terminal or inside the compressor, if there is sufficient
contaminant air present in the system and an electrical arc
occurs as the terminal vents.
Ignition cannot occur at the venting terminal without the
presence of contaminant air, and cannot occur externally
from the venting terminal without the presence of an
external ignition source.
Therefore, proper evacuation of a hermetic system is
essential at the time of manufacture and during servicing.
To reduce the possibility of external ignition, all open flame,
electrical power, and other heat sources should be
extinguished or turned off prior to servicing a system.
COMPRESSOR WINDING INSULATION TEST
The Inverter on the outdoor control board takes the position
signal from the UVW line, connected with the compressor.
If the system detects a malfunction on the compressor,
check the insulation resistance in accordance with the fol-
lowing procedure.
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing. Multiple power sources
may be present. Failure to do so may
cause property damage, personal injury
or death.
1. Remove the leads from the compressor terminals.
See warnings before removing compressor
terminal cover.
2. Using a Megometer, attach one lead to ground.
3. Using the other lead of the Megometer, check the insula-
tion between U to ground, V to ground, W to ground.
Compressor
Terminal
Unpainted
Refrigerant
Piping
TESTING COMPRESSOR WINDINGS INSULATION
NOTE: The 2, 3, and 4 ton compressor has a terminal on
the top. The 5 ton compressor has the terminals on the
side. If the insulation resistance of the compressor is less
than 100k Ohms between U to ground, V to ground, W to
ground, replace the compressor.
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
nearest point to the compressor.
2. Identify the leads and using an ohmmeter on the R x
10,000 scale or the highest resistance scale on your
ohmmeter check the resistance between each of the
three leads separately to ground (such as an unpainted
tube on the compressor).
3. If a ground is indicated, then carefully remove the com-
pressor 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.
5. Carefully retest for ground, directly between compressor
terminals and ground.
6. If ground is indicated, replace the compressor. The resis-
tance reading should be infinity. If there is any reading
on meter, there is some continuity to ground and com-
pressor should be considered defective.
