TM 9-4120-399-14
a. Test.
(1) Allow heaters to cool before touching.
(2) Check quick warm up heater (HR8) and thermostat as follows:
(a) Using a multimeter, check continuity b e t w e e n contacts D and E on P3
Continuity should be indicated. If continuity was indicated, skip steps (b) through
connector.
(d).
( b ) Check that jumper between heater halves is secure. Check jumper for
continuity. If continuity is not indicated, repair or replace jumper.
(c) Check continuity between P3 contact D and heater terminal A and contact E
and terminal B. If continuity is not indicated, repair or replace wire leads.
(d) Check continuity between heater half terminals.
If continuity is not indicated,
replace heater.
(e) Check heater (HR8) for visible damage, missing terminals or terminal covers,
and secure attachment of clamping hardware.
(f) Continuity check thermostat at connector P3 in per following Table 5-4.
TEMPERATURE
CONTINUITY SHOULD BE INDICATED
AT S10 THERMOSTAT
Contact
Contact
Contact
A to B
B to C
A to C
Above 70 8F
YES
NO
NO
(21.1 4.4c)
Below 50 5F
NO
NO
YES
(10 2.8C)
NOTE
Thermostat actuates at 70 8F (21.1 4.4C) and resets at
50 5F (10 2.8C).
If the thermostat fails any of the above tests, check that splices are properly installed. Repeat
above test. Replace compressor if thermostat is bad.