page 3 of 3 < PREVIOUS | NEXT >

Every 25,000 miles [40,000 Km] or when performing an oil drain, conduct a quick check of the fan drive.

Check for air leaks around the fan drive while air is applied to the fan drive.

1. Listen for leaks at the solenoid valve and filter assembly, and in the air hoses and fittings.
   
   
2. Feel for a leak with a wet finger or by applying soapy water and looking for bubbles.

Check the fan drive for discoloration or any other signs of slipping or overheating.
The fan drive may slip if incoming air pressure is below 90 PSI [6.21 bar] or if an air leak exists inside the fan drive. Never let a leak remain unattended.

Check the fan drive bearings.

1. Turn the fan blade in both directions and feel for worn hub bearings.
   
   
2. If the fan belts can be easily removed, remove the belts and check for worn sheave bearings.
   
   
3. Turn the sheave in both directions-if either the hub or sheave bearings are worn, repair or replace the fan drive with a Horton DriveMaster Super repair kit, a Horton remanufactured DriveMaster fan drive, a new DriveMaster fan drive or a PolarExtreme DriveMaster fan drive.

Check the fan drive friction facing for wear by measuring the thickness of the friction material. A new facing is 8.51 mm [~11/32"] thick. Replace the friction material if it has worn to less than 5.76 mm [~1/4"].

Check the electrical wiring at the thermal switch, air conditioning pressure switch, and solenoid valve. Be certain there are not any loose wires or connections.

Check the fan drive for proper engagement and disengagement.

Turn on the ignition switch but do not start the engine.

1. Be certain at least 90 PSI [6.21 bar] of air pressure is available in the truck's reservoir.
   
   
2. To manually engage and disengage the fan drive, open and close the electrical circuit going to the solenoid valve as follows:
   
   
   1. For a normally-open electrical system, use a jumper wire to short out the thermal switch or the air-conditioning refrigerant pressure switch.
      
      
   2. For a normally-closed electrical system, open the circuit by disconnecting a wire from one of the sensors or from the solenoid valve.

page 3 of 3 < PREVIOUS | NEXT >