TROUBLESHOOTING THE HMMWV - OD1616 - LESSON 1/TASK 1
Inspect the fan blade for damage.
If the fan blade is
damaged, replace it following the procedures contained in paragraph
3-73, page 3-120 of the TM.
Check for a clogged or blocked radiator system.
for evidence of a clog or block, refer to TM 750-254. For cleaning
and flushing instructions, refer to TB 750-651.
Step 6. Check the operation of the temperature gage. Refer to table
2-3, electrical system troubleshooting, malfunction 14, COOLANT
TEMPERATURE GAGE INOPERATIVE, page 2-40 of the TM.
Step 7. Check to see if the fan operates when the engine is running.
If the fan operates, notify IDS/IGS maintenance. If the fan does not
operate, proceed to step 8.
Check for continuity in the fan temperature switch.
Disconnect the engine harness leads 458A and 458B at the engine
temperature switch, located on the left side of the water crossover.
Using a multimeter, check for continuity between switch leads. With
the engine coolant temperature above 215 F, the switch should be open
With the coolant temperature below 215 F, the
switch should be closed (indicating continuity). If the switch does
not test correctly, replace the fan temperature switch following the
procedures contained in paragraph 4-30, page 4-49 of the TM.
Step 9. Disconnect the connectors between the fan drive solenoid and
the time delay on the left hand cowl. With the engine running, the
fan should operate. If the fan does not operate, proceed to step 12.
If the fan operates, proceed to step 10.
. Test the fan clutch solenoid. To do this, use a multimeter
and check for resistance between the connector terminals. Be sure to
check for resistance both ways. The resistance should be 75 8 Ohms
one way, and 12 1 Ohm the other way. If the resistance indicated
is not what it is supposed to be, replace the fan drive solenoid and
the hydraulic control valve following the procedures contained in
paragraph 8-20, page 8-48 of the TM. Now check the operation of the