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TM 9-4120-389-14
c.
Test.
(1)
Allow heaters to cool before touching.
(2)
Check compressor (B1), motor protector, heater (HR7), and thermostat (S7) as follows:
(a)
Disconnect P4 connector and harness from J4 connector located on compressor
junction box.
(b)
Remove wing nut from compressor junction box cover and gasket and pull junction box
cover from compressor.
(c)
Check that all wire connections are secure and in good condition.
(d)
Using multimeter, check continuity between connector J4 contacts to E, D to F, and E
to
F. Continuity should be indicated. If continuity is not indicated, check that wires are properly connected. If
wires are properly connected and continuity is still not indicated, replace compressor.
(e)
Check continuity between J4 contacts A and B. If there is no continuity and wires are
properly connected and there is continuity indicated, there is a internal short. Replace the compressor.
(f)
Check continuity between J4 contacts A, B, D, E, and F, and compressor canister. If
wires are properly connected and there is continuity indicated, there is an internal short. Replace the
compressor.
(g)
Check continuity between J4 contacts G and H. If there is continuity between these
pins, both the heater element and thermostat are all right. If there is no continuity between pins, bare the splice
between the heater lead and thermostat lead, and separately check for continuity between pin G and the splice,
and pin H, and the splice. If there is continuity between pin G and the splice, but not between pin H and the
splice, the heater element is all right and the thermostat is bad. If there is continuity between pin H and the
splice, but not between pin G and the splice, the thermostat is all right and the heater element is bad. If there is
no continuity between either pin and the splice, both the element and the thermostat are bad. If thermostat is
bad, replace thermostat. If heater is bad, replace heater.
5-68
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