SERVICE BULLETIN - Autocar Truck

1 1 of 9 SERVICE BULLETINDECEMBER, 2005SB 4-208-001 Autocar , LLC551 South Washington StreetP. O. Box 190 Hagerstown, IN 47346-0190AC-SB-263-0512-P86 ATTENTION: SERVICE MANAGERS / PARTS MANAGERSSUBJECT: CERTAIN Autocar WX AND WXLL MODEL VEHICLES EQUIPPED WITH THE CUMMINS ENGINE THAT EXPERIENCE FAN CLUTCH FAILURESS ervice BULLETIN Information: SERVICE Bulletins are product modifications and/or product improvements that Autocar has determined will enhance the operation of the Truck . This BULLETIN provides information on a solution to prevent failure of Horton fan clutches in the field.

2 After repetitive clutch failures on certain trucks, an investigation determined the cause to be clogged exhausts on the fan clutch solenoid valves. It was found that as the fan clutch solenoid valve cycled to engage the fan clutch, the restriction in the solenoid valve exhaust caused air not to escape fully from the clutch actuator. This caused the fan clutch not to engage fully, thus damaging the clutch. Proper orientation of the fan clutch solenoid valve and a clean solenoid valve exhaust solves the problem. It is also recommended that the minimum fan clutch on time be set for 120 :See the Repair Procedure on Page 2.

3 Parts:Part numbers listed below are preferred over the Kysor single tab solenoid valves that might be fitted to older trucks. Part number for dual tab solenoid Kysor brand, 3935020 orPart number for dual tab solenoid Horton brand, A-2080087-0012 of 9 SERVICE BULLETINDECEMBER, 2005SB 4-208-001 Autocar , LLC551 South Washington StreetP. O. Box 190 Hagerstown, IN 47346-0190AC-SB-263-0512-P86 WARNINGTo prevent eye injury, always wear eye protection when performing vehicle maintenance, SERVICE or Procedure1. Park the vehicle on a level surface.

4 Turn off the engine, apply the parking brakes, and chock the rear tires to keep the vehicle from Bleed the air from the air system reservoirs. When the system is completely drained, close the drain Tilt the cab forward. See the instructions beginning on page 6 for instructions in raising and lowering the working on a vehicle, set the parking brake, place the transmission in neutral and block the wheels. Failure to do so can result in unexpected vehicle movement and can cause serious personal injury or and lock the battery disconnect switch to disconnect the battery power to the Truck to limit the risk of electrical shock and of 9 SERVICE BULLETINDECEMBER, 2005SB 4-208-001 Autocar , LLC551 South Washington StreetP.

5 O. Box 190 Hagerstown, IN 47346-0190AC-SB-263-0512-P864. With the cab tilted forward, locate the fan clutch solenoid valve towards the front of the engine (Figure 1).5. Inspect the fan clutch solenoid valve mounting to ensure the exhaust port orientation is horizontal. If not, re-orientate the valve. The correct orientation is shown in Figure VALVECONNECTORINSTALL 150 psiGAUGE HEREFAN CLUTCHEXHAUSTPORTF igure 14 of 9 SERVICE BULLETINDECEMBER, 2005SB 4-208-001 Autocar , LLC551 South Washington StreetP. O. Box 190 Hagerstown, IN 47346-0190AC-SB-263-0512-P866.

6 If the valve is equipped with an exhaust diffuser remove and discard it (Figure 2).7. If the vehicle is equipped with a single tab mount solenoid valve (Figure 2) it is recommended that it be replaced with a dual tab mount solenoid Install a 150 psi capacity air pressure gauge in the line between the fan clutch and the fan clutch solenoid valve (Figure 1) with a long enough tube to ensure the gauge can be positioned where it can be monitored from the outside with the cab Lower the cab and lock it in place. Refer to page 6 for instructions to safely lower and lock the cab.

7 Ensure that the line to the pressure gauge or the pressure gauge itself is not pinched by the lowered cab, and that they are clear of moving Unlock the battery disconnect switch, turn it to switch on the power to the Truck and start the When the engine reaches operating temperature, the fan will cycle on and off. As the fan cycles, monitor the air pressure gauge mounted between the fan clutch solenoid valve and the fan clutch. When the fan cycles off, system pressure should match the pressure in the line between the fan clutch and the fan clutch solenoid valve.

8 When the fan cycles on there should be no electrical signal to the fan clutch solenoid valve and no air pressure to the fan TABDIFFUSERF igure 25 of 9 SERVICE BULLETINDECEMBER, 2005SB 4-208-001 Autocar , LLC551 South Washington StreetP. O. Box 190 Hagerstown, IN 47346-0190AC-SB-263-0512-P8612. If residual air pressure is present with the fan on, follow steps 1 through 5, taking note of the warnings listed. Make sure the exhaust port on the fan clutch solenoid valve is clear and free of obstructions. If the exhaust is clear but the problem persists, replace the fan clutch solenoid valve with one of the two parts listed under Parts on page 1.

9 Remember to drain the air from the system before disconnecting any air Repeat the test procedure described in steps 9 through Once the problem is resolved, drain the air from the air reservoirs and remove the air pressure gauge. Remove the air pressure gauge and reconnect the fan clutch actuator to the solenoid valve air line, routing and clipping the air line with at least one inch of clearance from objects that might move relative to engine or air line when running the engine and cycling the fan Lower and lock the cab in place.

10 See page 6 for of 9 SERVICE BULLETINDECEMBER, 2005SB 4-208-001 Autocar , LLC551 South Washington StreetP. O. Box 190 Hagerstown, IN 47346-0190AC-SB-263-0512-P86 Tilting CabGeneralNOTE: Remove or secure all loose articles and close all doors before tilting the cab. The area above and ahead of the cab must be clear. The front wheels should be pointed in the straight ahead position. Read the label affixed to the seat base for more cab tilting working on a vehicle, set the parking brake, place the transmission in neutral and block the wheels.