Daikin DAR09 - S-18 D Operation Test; S-18 E Checking 3-Phase Scroll Compressor Rotation

65
SERVICING
1. Operate the system and measure compressor current. Cycle
the unloader ON and OFF at 10 second intervals. The com-
pressor amperage should go up or down at least 25 percent.
2. If step one does not give the expected results, shut unit o.
Apply 18 to 28 volt ac to the unloader molded plug leads and
listen for a click as the solenoid pulls in. Remove power and
listen for another click as the unloader returns to its original
posion.
3. If clicks can’t be heard, shut o power and remove the con-
trol circuit molded plug from the compressor and measure
the unloader coil resistance. The resistance should be 32 to
60 ohms, depending on compressor temperature.
4. Next check the molded plug.
a. Voltage check: Apply control voltage to the plug wires
(18 to 28 volt ac). The measured dc voltage at the female
connectors in the plug should be around 15 to 27 vdc.
b. Resistance check: Measure the resistance from the end
of one molded plug lead to either of the two female connec-
tors in the plug. One of the connectors should read close to
zero ohms while the other should read innity. Repeat with
other wire. The same female connector as before should
read zero while the other connector again reads innity.
Reverse polarity on the ohmmeter leads and repeat. The
female connector that read innity previously should now
read close to zero ohms.
c. Replace plug if either of these test methods doesn’t
show the desired results.
S-18D OPERATION TEST
If the voltage, capacitor, overload and motor winding test fail to
show the cause for failure:
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 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 protecve 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 respecve leads.
3. Connect good capacitors of the right MFD and voltage rang
into the circuit as shown.
4. With power ON, close the switch.
WARNING
Line Voltage now present.
a. If the compressor starts and connues to run, the cause for
failure is somewhere else in the system.
b. If the compressor fails to start - replace.
COPELAND COMPRESSOR
03 A 12345 L
YEAR
MONTH
SERIAL
NUMBER
PLANT
S-18E CHECKING 3-PHASE SCROLL
COMPRESSOR ROTATION
Verify the proper rotaon of Copeland scroll compressors as
follows:
NOTE: The compressor may run backwards (noisy operaon) for
1 or 2 seconds at shutdown. This is normal and does not harm
the compressor.
1. Install gauges and verify that the sucon pressure drops
while the discharge pressure increases.
2. Listen for normal compressor sound levels. Reverse rotaon
results in elevated or unusual sound levels.
3. Reverse rotaon will result in substanally reduced amp
draw from tabulated values.
To correct improper rotaon, switch any two power supply leads
at the outdoor unit contactor.
The 3-phase scroll compressors are direcon of rotaon sen-
sive. They will rotate in either direcon depending on the
phasing of the power. There is no negave impact on durability
caused by operang 3-phase compressors in reversed rotaon.
The compressor’s internal protector will trip, de-energizing the
compressor. Connued operaon of 3-phase scroll compressors
with the rotaon reversed will contribute to compressor failure.
All 3-phase scroll compressors should be checked for correct
phase rotaon.
S-18 TESTING CRANKCASE HEATER
(OPTIONAL ITEM)
The crankcase heater must be energized a minimum of four (4)
hours before the condensing unit is operated.
Crankcase heaters are used to prevent migraon or accumula-
on of refrigerant in the compressor crankcase during the o
cycles and prevents liquid slugging or oil pumping on start up.
A crankcase heater will not prevent compressor damage due to a
oodback or over charge condion.