TM 9-4120-407-14
(c) Maintain the temperature at the thermostatic switch (2) to any point below 45 F (7 C).
Using a multimeter set to measure resistance, check continuity across lead (1) terminals (3).
Continuity should be indicated.
(2) Compressor Heater.
(b) Using multimeter set to measure resistance, check resistance across two lead (4) ends. A
resistance of between 36 and 44 ohms should be indicated.
(3) Compressor Assembly and Crankcase Heater.
(a) Tag and disconnect wiring harness connector P4 (5) Figure 4-23 from connector J4 (6).
(7) motor windings.
NOTE
The compressor motor windings use an integral thermal overload to
protect them. This overload will open if the compressor overheats
and will reset once it has cooled. Tests will not be conclusive if
conducted on a compressor that feels hot.
1 Check continuity between connector J4 (6) pins D to E, D to F, and E to F. Continuity should
be indicated.
(6) pin D, E, and F in turn. No continuity should be indicated.
3 Replace compressor (7) if windings fail above tests.
heater (8).
1 Check resistance between connector J4 (6) pins G and H. A resistance of between 950 and
1,450 ohms should be indicated.
(6) pin G and H in turn. No continuity should be indicated.
(4) Replace component(s) that fail any of the above tests.
b. Repair. The only repairs that can be performed on the compressor are replacement of external
damaged or missing components.
NOTE
Remove components only as necessary for repair/replacement, or for
transfer to a replacement compressor.
(1) Connector (J4) and Wiring Harness.
(a) Tag and disconnect wiring harness connector P4 (5) Figure 4-23 from connector J4 (6).
(b) Remove four screws (9), lock washers (10), flat washers (11), and cover (12). Discard lock
washers.
4-73