TM 9-4120-404-14
3-43. RELAY (K2). - Continued
(1) Tag and disconnect wires attached to relay (1).
(2) Remove four screws (2), four lock washers (3), four flat washers (4) and relay (1) from unit.
(3) Remove diode (5) from relay (1).
b. Test.
(1) Using a multimeter set on lowest OHMS scale, check for continuity across terminals A1 & A2, B1 & B2, and
C1 & C2. Continuity should not be indicated.
(2) Check for continuity between terminal X1 and X2. There should be a low ohms reading.
(3) Apply 28 vdc power across X1 and X2.
(4) Using a multimeter set on lowest ohms reading scale, check the reading across terminals A1 & A2, B1 &
B2, and C1 & C2. Continuity should now be indicated.
(5) Replace relay if it fails any of the above tests.
(6) Use a multimeter to test that diode (5) has infinite resistance when tested. Reverse multimeter test leads
and check that diode now has continuity.
c. Installation.
CAUTION
Improper diode installation will damage unit. Be sure "+" end of diode is installed
to terminal X1 of relay.
(1) Install diode (5) onto relay (1).
(2) Place relay (1) into position in unit and install four screws (2), four lock washers (3), and four flat washers
(4).
(3) Refer to wire tags installed during removal and reconnect wires to relay (1) and remove tags.
(4) Install rear cover (see para. 3-27).
(5) Reconnect air conditioner to power source.
3-120
