SERVICING
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 PLANT NUMBER
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 accumu- lation 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
When stuck in the
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.
If no voltage is registered at the coil terminals, check the operation of the thermostat an the continuity of the connect- ing wiring from the "O" terminal of the thermostat to the unit.
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
To check the defrost control for proper sequencing, proceed as follows: With power ON; unit not running.
1.Jumper defrost thermostat by placing a jumper wire across the terminals "DFT" and "R" at defrost control board.
2.Connect jumper across test pins on defrost control board.
3.Set thermostat to call for heating. System should go into defrost within 21 seconds.
4.Immediately remove jumper from test pins.
5.Using VOM check for voltage across terminals "C & O". Meter should read 24 volts.
6.Using VOM check for voltage across fan terminals DF1 and DF2 on the board. You should read line voltage (208- 230 VAC) indicating the relay is open in the defrost mode.
7.Using VOM check for voltage across "W2 & C" terminals on the board. You should read 24 volts.
8.If not as above, replace control board.
9.Set thermostat to off position and disconnect power before removing any jumpers or wires.
NOTE: Remove jumper across defrost thermostat before returning system to service.
S-25 TESTING DEFROST THERMOSTAT
1.Install a thermocouple type temperature test lead on the tube adjacent to the defrost control. Insulate the lead point of contact.
2.Check the temperature at which the control closes its contacts by lowering the temperature of the control. Part
# 0130M00009P which is used on 2 and 2.5 ton units should close at 34°F ± 5°F. Part # 0130M00001P which is used on 3 thru 5 ton units should close at 31°F ± 3°F.
3.Check the temperature at which the control opens its contacts by raising the temperature of the control. Part # 0130M00009P which is used on 2 and 2.5 ton units should open at 60°F ± 5°F. Part # 0130M00001P which is used on 3 thru 5 ton units should open at 75°F ± 6°F.
4.If not as above, replace control.
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