Defrost Drain Heater

TM 10-4110-262-13&P

0029 00

NOTE

Controller grounds contactor coil through OR circuit.

5. If heater contactor coil has no power, check fuse 4.

6. If contactor has power but no ground, check "OR" circuit and controller.

7. If contactor has power and ground, replace contactor.

8. If load side of overload has power, disconnect power to RU.

9. Disconnect wires to heater rods and ohm rods separately. Replace as necessary.

10. If heater rods are correct, replace conductor from the overload to the heater rods.

Defrost Drain Heater

1. Check for 24 VDC at the drain pan heater connectors.

2. If voltage is present, replace heater resistive wires.

3. If voltage is not present, check voltage on load side of fuse 3.

4. If no voltage is present on load side of fuse 3, replace the fuse.

5. If voltage is present, check normally open contacts of power relay and defrost relay. Replace faulty

relays as needed.

6. If relay passes checks, check power on connector C1 circuit 26.

7. If power is present, replace conductor to heater connector.

8. If power is not present, replace the PC board.

Contactors

1. Index the unit to run in either the heat or a cool mode depending on the contractor being checked.

2. Verify the coil has a voltage (24 VDC).

3. Using a multimeter, determine if 208/230 VAC is present on the line side of contractor between L1,

L2, L3 (heat contractor will be L2 and L3).

4. If proper voltage is not present in Step 3, then troubleshoot loss of incoming power.

5. If proper voltage is present, then disconnect and tape T1A, T2A, and T3A (heat contractor is U1 and

V1) wires.

6. Check for 208/230 VAC is present on the load side of contractor between terminals 2, 4, and 6 (heat contractor 2

and 4).

7. If proper voltage is not present, then replace contractors.

0029 00-7