Unit Controller

TM 10-4110-262-13&P

0029 00

6. If 24 VDC is detected, check for continuity between C3 (terminal 2) to the main unit to ground.

7. If no continuity is detected, locate and repair the wire coming/going from the RU control box to the DTS contactor.

8. If no continuity is detected then remove the jumper wire installed in step 3 of the Defrost Termination Switch

section above and check between C3 (terminal 2) and wire 12 located in the DTS harness.

9. If continuity is not found, then replace the wire.

10. If continuity is found, check for continuity between wire CHB located in the DTS harness and ground.

11. If no continuity is found, replace the wire.

12. Check for 24 VDC at pin 8 (grey wire) located at the RU controller and pin 9 (white wire ground).

13. If 24 VDC is detected between pin 8 and pin 9, disconnect the main power from the RU, remove the 10-pin

connector to isolate the circuit and check continuity between pin 8 and C3 pin 1 on the RU control board.

14. If no continuity is detected, then make sure the pin connector is firmly seated in both harness connectors.

15. If continuity is still not detected, replace wire harness.

Unit Controller

1. Remove the controller from the unit controller enclosure.

2. Ensure that all wires are firmly seated in the terminal connector.

3. Recheck controller operation. If unit controller is not functioning:

a. Disconnect the 10-pin wire harness pin connector from the back of the unit controller.

b. Verify 24 VDC is present between terminals 2 (positive) and 9 (ground).

If proper power is not present, troubleshoot 24 VDC power supply.

With an ohmmeter, check continuity between terminal 9 (w) and unit ground.

e. Pull the controller fuse 4/1 out and check continuity between the fuse.

If no continuity, replace the fuse. If continuity, replace the unit controller.

END OF WORK PACKAGE

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