TM 9-4520-260-13
4-24. OVERHEAT SWITCH AND FLAME SWITCH - CONTINUED
TESTING
NOTE
The overheat switch is a normally closed switch at normal ambient temperatures.
1. Using a multimeter set on the OHMS scale check for continuity between terminals A and B of the overheat switch (2).
There shall be continuity between terminals A and B at normal ambient temperatures.
2. Replace an overheat switch that does not exhibit continuity between terminals A and B.
NOTE
Flame switch is a normally opened switch at normal ambient temperatures.
3. Using a multimeter set on the OHMS scale check for continuity between stripped wire ends C and D of flame switch
(6). There shall not be continuity between wire ends C and D at normal ambient temperatures.
4. Replace a flame switch that exhibits continuity between stripped wire ends C and D.
REMOVAL (Figure 4-21)
1. Disconnect and tag (Item 13, Appendix E) two wires (1) from the overheat switch (2).
2. Remove two screws (3) and two washers (4) securing overheat switch (2) to heat exchanger (5) and remove switch
(2).
3. Remove flame switch (6) by removing nut (7) and washer (8).
4. Disconnect and tag (Item 13, Appendix E) two wires (9) from ECU.
5. Remove wires (9) from grommet (10). Remove the grommet (10).
INSTALLATION
1.
Install flame switch (6) and secure with nut (7) and washer (8).
2.
Install grommet (10) and position flame switch wires (9) through the grommet (10). Connect wires to the ECU.
3.
Remove tag and connect violet wire (C) to terminal 3 of the ECU.
4.
Remove tag and connect black wire with (D) to terminal 7 of the ECU.
5.
Install overheat switch (2) to heat exchanger (5), and secure with two washers (4) and screws (3). Connect wires (1)
to overheat switch (2).
4-49
