Checking Reversing Valve And Solenoid; Testing Defrost Control; Testing Defrost Thermostat; Checking Heater Limit Control(S) - Daikin DAR09 Service Instructions Manual

SERVICING
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 cool-
ing 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 switch-
ing 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 ComfortNetT™ heat pumps wired in legacy
- If no voltage is registered at the coil terminals, check the opera-
tion of the thermostat and the continuity of the connecting
wiring from the "O" terminal of the thermostat to the unit.
S-24

TESTING DEFROST CONTROL

LEGACY MODELS:
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"/"R-DFT" 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". Me-
ter 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 "W"/"W2" & "C" termi-
nals 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 return-
ing 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 or B1370803 which
is used on 3 thru 5 ton units should close at 31°F ± 3°F.
3. Check the temperature at which the control closes its
contacts by lowering the temperature of the control. Part #
0130M00085, which is used onunits with 5 mm coils, should
close at 30°F ± 5°F.
4. 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 or B1370803 which
is used on 3 thru 5 ton units should open at 75°F ± 6°F.
5. Check the temperature at which the control opens its
contacts by raising the temperature of the control. Part #
0130M00085, which is used on units with 5 mm coils, should
open at 60°F ± 5°F.
6. If not as above, replace control.
S-50

CHECKING HEATER LIMIT CONTROL(S)

(OPTIONAL ELECTRIC HEATERS)
Each individual heater element is protected with an automat-
ic rest limit control connected in series with each element to
prevent overheating of components in case of low airflow. This
limit control will open its circuit at approximately 150°F. to 160°F
and close at approximately 110°F.
WARNING
Disconnect ALL power before servicing.
1. Remove the wiring from the control terminals.
2. Using an ohmmeter test for continuity across the normally
closed contacts. No reading indicates the control is open
- replace if necessary. Make sure the limits are cool before
testing.
IF FOUND OPEN - REPLACE - DO NOT WIRE AROUND.
S-52

CHECKING HEATER ELEMENTS

Optional electric heaters may be added, in the quantities shown
in the spec sheet for each model unit, to provide electric resis-
tance heating. Under no condition shall more heaters than the
quantity shown be installed.
66