8206noco.fm Page 203 Thursday, July 2, 1998 1:19 PM
SYMPTOM RELATED DIAGNOSTICS ON/OFF FAN CONTROL VERBAL COMPLAINT (continued) Test 2
Test 4
Checking the energized solenoid operation
Checking the de-energized solenoid operation 1. Disconnect the jumper wire from pin B to ground (do not reconnect the solenoid connector). 2. With the coolant temperature less than 170°F (77°C) attempt to turn the fan by hand.
If the fan still turns freely, proceed to Test 9. If the fan does not turn freely, proceed to Test 8.
Test 5 Checking for a failed fan clutch Figure 322 — Jumpers from Pin A to Pin A and Pin B to Ground
1. Disconnect the discharge air hose which runs from the solenoid to the fan clutch. KYSOR FAN CLUTCH:
Never place hands near the fan or belts while the engine is running. 1. Turn the ignition key to the OFF position. 2. Connect a jumper between pin A of the engine connector and pin A of the solenoid connector. 3. Connect a jumper from pin B of the solenoid connector to a good ground. 4. Start the engine. Allow chassis air pressure to build up to at least 90 psi. 5. Stop the engine. 6. Turn the ignition key to the ON position. 7. With the coolant temperature less than 170°F (77°C) attempt to turn the fan by hand.
If the fan is disengaged and turns freely, proceed to Test 4.
If air flows out of the solenoid discharge port with the ignition key in the ON position, there is a problem with the fan clutch, or the hose running from the solenoid to the fan clutch is pinched or damaged. Locate and repair the problem. Retest to be sure the problem has been corrected. If air does not flow out of the solenoid discharge port, proceed to Test 11. HORTON FAN CLUTCH:
If air flows out of the solenoid discharge port, the valve may be plumbed improperly. Reverse the vent and air supply lines on the solenoid and retest. Verify that air does not flow out of the discharge port when the jumper wire is connected to ground, and that air flows when the jumper wire is removed. Retest to be sure the problem has been corrected. If air does not flow out of the solenoid discharge port with the ignition key in the ON position, there is a problem with the fan clutch. Locate and repair the problem. Retest to be sure the problem has been corrected.
If the fan does not turn freely, proceed to Test 5. Page 203
