85
SERVICING
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
rating into the circuit as shown.
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.
COPELAND COMPRESSOR
03 A 12345 L
YEAR
MONTH SERIAL
NUMBER
PLANT
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 migration or accumulation
of refrigerant in the compressor crankcase during the off cycles
and prevents liquid slugging or oil pumping 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
continuous. If not, replace.
NOTE:
The positive temperature coefficient crankcase heater is a
40 watt 265 voltage heater. The cool resistance of the heater will
be approximately 1800 ohms. The resistance will become greater
as the temperature of the compressor shell increases.
S-21 CHECKING REVERSING VALVE AND
SOLENOID
Occasionally the reversing valve may stick in the heating or
cooling position or in the mid-position.
When stuck in the mid-position, part of the discharge gas from
the compressor is directed back to the suction side, resulting in
excessively high suction pressure. An increase in the suction line
temperature through the reversing valve can also be measured.
Check operation of the valve by starting the system and
switching the operation from COOLING to HEATING cycle.
If the valve fails to change its position, test the voltage (24V)
at the valve coil terminals, while the system is on the COOLING
cycle.
All heat pumps and ComfortNet™ heat pumps wired in
legacy
- If no voltage is registered at the coil terminals, check the
operation of the thermostat and the continuity of the connecting
wiring from the “O” terminal of the thermostat to the unit.
ComfortNet heat pumps only
- Check voltage (24VAC) at the
non-insulated terminal E22 on the UC control board (RVS on
silkscreen) and “C” terminal on the 7-pin or 4-pin connector on
the UC control.
If voltage is registered at the coil, tap the valve body lightly while
switching the system from HEATING to COOLING, etc. If this fails
to cause the valve to switch positions, remove the coil connector
cap and test the continuity of the reversing valve solenoid coil. If
the coil does not test continuous - replace it.
If the coil test continuous and 24 volts is present at the coil
terminals, the valve is inoperative - Replace it.
S-24 TESTING DEFROST CONTROL
LEGACY MODELS:
COMFORTNET™ UNITS:
To check the defrost control for proper sequencing, proceed as
follows: With power ON; unit not running.
1. Set thermostat to call for heating.
2. Press TEST and RECALL buttons simultaneously for
approximately 3 seconds, then release them. System
should go into defrost immediately.
3. Using VOM check for voltage across terminals “C & O”.
Meter should read 24 volts (Skip this step if system a fully
communicating system).
4. Visually inspect to see that the frost is gradually melting
on the coil and the compressor is running.
5. Using VOM check for voltage across “W2 & C” terminals
on the board. You should read 24 volts.
6. If not as above, replace control board.
7. Set thermostat to off position and disconnect power
before removing any jumpers or wires.
