SERVICING
44
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 S-17 before removing compressor
terminal cover.
2. Check the wiring connection of UVW on the compressor termi-
nal.
3. Check the insulation resistance of the compressor between
the compressor terminal and unpainted refrigerant piping.
U
W
V
COMP
OHMMETER
TESTING COMPRESSOR WINDINGS
NOTE:
The 2, 3, and 4 ton compressor has a terminal on the top.
The 5 ton compressor has a terminal on the side.
If the insulation resistance of the compressor is less than 100 k
Ohms, replace the compressor.
NOTE:
If an open compressor is indicated, allow ample time for
the internal overload to reset before replacing compressor.
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 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 compressor
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 resistance
reading should be infinity. If there is any reading on meter,
there is some continuity to ground and compressor should
be considered defective.
OHMMETER
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.
S-18 TESTING CRANKCASE HEATER (5TON
ONLY)
The crankcase heater must be energized a minimum of 2 hours
before the unit is operated. Crankcase heaters are used to prevent
migration or accumulation of refrigerant in the compressor crank-
case during the off cycles and prevents liquid slugging or oil pump-
ing on start up. A crankcase heater will not prevent compressor
damage due to a floodback or over charge condition.
WARNING
Disconnect ALL power before servicing.
1. Disconnect the heater lead in wires.
2. Using an ohmmeter, check heater continuity - should test con-
tinuous. If not, replace.
NOTE:
The positive temperature coefficient crankcase heater is a
33 watt 240 voltage heater. The cool resistance of the heater will
be approximately 1745 ohms. The resistance will become greater
as the temperature of the compressor shell increases.
