TM 9-4120-407-14
4-7. LOGIC BOX ASSEMBLY TESTING AND REPLACEMENT. (Cont)
NOTE
If the logic box assembly fails any of the following tests, the entire
assembly must be replaced. Do not continue testing beyond a failure
point.
(2) Heat Mode Test.
(a) Set TEMPERATURE control to WARM position and AMBIENT control to COOL position,
MODE switch to HEAT and switches S1 thru S6 to OFF position (contacts closed) and switch
S7 to ON position (contact open), then turn test fixture power on. After a 2 second delay,
LED' 1 and 7 shall illuminate and multimeter shall read 6.3 vdc or higher.
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(b) Set TEMPERATURE control to COOL position. LED 1 shall turn off. LED 7 shall remain
illuminated.
(c) Rotate TEMPERATURE control slowly towards WARM position until LED 1 illuminates.
Slowly rotate AMBIENT control toward WARM position until LED 1 turns off. LED 7 shall
remain illuminated.
(d) Rotate TEMPERATURE control towards WARM until LED 1 illuminates again. Place S3 in the
ON position (contacts open). This step should have no effect on operation. LED' 1 and 7
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shall remain illuminated.
(e) Rotate AMBIENT control to COOL position and place S3 in the OFF position. Place S1 in the
ON position. LED' 1 and 7 shall turn off and in 10 seconds. LED' 3 shall illuminate.
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(f) Reset logic by turning rotary MODE switch to OFF RESET position. Place S1 in the OFF
position. Move TEMPERATURE control to WARM position. Set MODE switch to HEAT.
LED' 1 and 7 shall illuminate following a 2 second delay.
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(g) Place S1 in the ON position for 2 seconds then place S1 in the OFF position. LED' 1 and 7
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shall turn off for 10 seconds then illuminate.
(h) Place S2 in the ON position for 2 seconds then turn S2 OFF again. LED 1 shall turn off. After
10 seconds, LED 7 shall turn off for 2 seconds. Then both LED' turn on again.
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(i) Place S2 in ON position. LED 1 shall turn off and LED 7 shall remain illuminated. LED 3
shall illuminate after 10 seconds.
(j) Reset by turning rotary MODE switch to OFF RESET position. Place S2 in the OFF position.
Maintain TEMPERATURE control in WARM position. Set MODE switch to HEAT. LED' 1
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and 7 shall illuminate after a 2 second delay.
(k) Place S4 in the ON position. The following routine shall occur:
1 LED 1 shall turn off and LED 7 shall remain illuminated.
2 For the next 8 seconds: LED 4 illuminates. LED 7 remains illuminated.
3 For the next 2 seconds: LED' 4 and 7 turn off.
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4 For the next 2 seconds: LED 4 shall continue to be off. LED 7 shall illuminate.
5 Steps 2 thru 4 shall repeat twice. Then LED 4 illuminates and LED 7 remains illuminated.
End of routine.
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