![background image](http://html1.mh-extra.com/html/daikin/m-series/m-series_service-and-troubleshooting_3237153025.webp)
SERVICING
25
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.
Testing Defrost Control
NOTE: PCBDM133 defrost controls have a three (3)
minute compressor off cycle delay.
NOTE: The PCBDM133 defrost controls are shipped
from the factory with the compressor delay option
selected. This will de-energize the compressor
contactor for 30 seconds on defrost initiation and
defrost termination. If the jumper is set to Normal,
the compressor will continue to run during defrost
initiation and defrost termination. The control will also
ignore the low pressure switch connected to R-PS1
and PS2 for 5 minutes upon defrost initiation and 5
minutes after defrost termination.
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. Remove jumper from timer pins and jump across
test pins on defrost control board.
Note:
Do not
use screwdriver or field supplied jumper to test the
control.
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 “W”/”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.
Remove jumper from defrost thermostat and replace
timer jumper to the desired defrost time.
NOTE: Remove jumper across defrost thermostat
before returning system to service.
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. It
should close at approximately 30°F.
3. Check the temperature at which the control opens its
contacts by raising the temperature of the control. It
should open at approximately 60°F.
4. If not as above, replace control.
Refrigeration Repair Practice
DANGER
Always remove the refrigerant charge in a proper manner
before applying heat to the system.
When repairing the refrigeration system:
WARNING
Disconnect ALL power before servicing.
1. Never open a system that is under vacuum. Air and
moisture will be drawn in.
2. Plug or cap all openings.
3. Remove all burrs and clean the brazing surfaces
of the tubing with sand cloth or paper. Brazing