TM 5-3805-262-20
3-24. ACCESSORIES TROUBLESHOOTING (CONT)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
8. DEFROSTER MOTOR DOES NOT OPERATE (Cont).
S t e p 2 . ( C o n t ) .
Set DEFROSTER switch to ON position.
Check if defroster motor and heater fan operate.
a. If both defroster motor and heater fan operate, problem was
momentary short in circuit. If circuit breaker blows again,
problem is in circuit associated with circuit breaker.
Disconnect wires from circuit breaker, one at a time to isolate
problem to associated circuit: a u x i l i a r y s t e e r i n g , i n s t r u m e nt
panel cluster (located on left instrument panel), voltmeter, cab
relay solenoid, or electric fuel pump.
b. If defroster motor and heater fan do not operate and circuit
breaker did not blow, go to step 3 below.
Step 3.
Remove engine left side panels (page 9-14).
3-170
Connect multimeter across terminals of cab
b r e a k e r.
Multimeter should indicate zero.
30 ampere circuit
a. If multimeter indicates 24 volts, circuit breaker is open. Go to
step 4 below.
b. If multimeter indicates zero, replace cab relay (page 5-26).
