Horton Fan Clutch Troubleshooting & Service Instructions

The Horton Fan Clutch is important for the functioning and operation of your truck. Yet it is often overlooked and is among one of the least maintained components. With this blog, we attempt to explain how the Horton fan clutch works, what maintenance it requires, and, more importantly, what to keep an eye on.

A Horton fan clutch’s primary function is to engage & disengage the engine fan with an air-actuated solenoid valve controlled by a clutch. In all modern vehicles, the clutch solenoid receives a signal to turn on or to turn off the engine’s ECU. In older trucks, the signal is sent from the temperature sensor.

A Fan Clutch engages the fan and makes it turn when the valve opens; it pushes the PFD (Piston Friction Disc) against the friction material and also sends air pressure to overcome a spring. It disengages when the valve is closed, which allows the solenoid to exhaust air and let the spring return.

Most vehicles today have a manual override switch, which allows the driver to activate the fan when approaching a hill to bring the operating temperature of the engine down. Conversely, on the way back, a professional driver should manually activate the fan to help aid engine retardation because the fan soaks up 30- 40 horsepower.

Horton fan clutch


Horton Fan Clutch problems

The temperature-sensitive spring is often one of the potential culprits when it comes to fan clutch problems. Additionally, as the consistency of thermal fan clutches oil slowly degrades over the years, the clutch can begin to slip more than usual, eventually slowing down to a point where it doesn’t keep up with the cooling needs of the engine. Other symptoms may include things like loose clutches or oil leakage, which are known to cause a bit of a wobble.

Further, Clutch slippage is one of the most common causes of premature failure in a Horton fan clutch. It’s caused by excessive heat, but it’s not all bad news. Since the mid-1990s, all HTS type fan clutches with a 9.5-inch (241mm) diameter have been equipped with the System Sentry to help prevent clutch failure. System Sentry disengages the fan clutch if it encounters excessive heat build-up since it is designed to act as a thermal fuse.

When the System Sentry releases the fan clutch, it is to protect your investment. This protective action makes you aware of a problem so that you troubleshoot and repair it immediately. Catching problems in the early stages can keep damage & downtime to a minimum.


Horton Fan Clutch Troubleshooting

A System Sentry ‘meltdown signal’ means something is wrong, and action is required to determine what went wrong.

Clutch Slippage

A fan clutch needs 100 PSI (6.8 bars) for solid engagement. Look for a problem that causes partial engagement, most times, air leaking past the solenoid valve seals into the airline and creates a pressure build-up. If there is a pressure drop caused by partial disengagement, the reasons behind this could be a defective solenoid, up-stream air leaks, airline blockage, air leaks from the fan clutch body itself, or low air pressure.

Fan Blades

Fan Blades should be checked for correct clearance to the shroud, radiator & other engine components. Check, locate & remove anything that may be obstructing the fan blade. Also, check for splits or cracks in the fan blades that might cause the fan to run out of balance.

How to perform preventive maintenance on a truck’s engine cooling system?

The Horton Fan Clutch should be routinely inspected at 200,000km intervals.

Feel for smooth rotation of bearings by removing & plugging the airlines at the fan clutch input, rotating the pump pulley, and loosening the fan belts. Repeat this procedure for the front section of the fan clutch.

Check for wear & tear of friction facing. The approximate thickness of the friction facing should be 4mm. If it isn’t, drain the inline air-filter daily to release any moisture.


Manual Lockup procedure

If for any reason, the Horton fan is still not engaging, for instance, when the System Sentry fuse has released, you can manually engage the fan with the two bolts provided in the emergency bolt kit.

To manually engage your fan clutch, first, disconnect & plug the airline to the fan clutch. Install two Grade-8 (5/16) Whitworth socket head cap screws by aligning the two bolt-holes in the front section of the fan clutch with the two tapped holes located in the pulley sheave.

Tightening screws very firmly, and clamping the clutch, not the screws, provides the turning force. If you need to purchase a replacement set of lockup bolts, their part number is F21610.

Further, if the Horton Fan Clutch still fails, there are plenty of options to replace it. But with preventive maintenance, and the following “Service Instructions,” you can detect and solve potential problems well before they put your truck out of commission.

Here’s a simple, step-by-step guide –

1. Check the state of the coolant hoses, radiator cooling fan, expansion tank, water pump shaft, AC system, belt, belt tensioner & thermostat for any visual signs of corrosion, wear & tear, or other defects.

2. Examine the fan for any defects, chips, or contamination build-up.

3. If the fan clutch is ‘pneumatically-operated,’ take a look at the air supply system of the clutch.

It includes checking the electric circuit to the solenoid valve, the airline to the solenoid valve, and the airline to the fan clutch.

4. Examine the fan clutch for defects

Including these checks as part of your regular servicing or preventive maintenance program can drastically increase the life of a truck’s engine cooling system and reveal problems before they cause a breakdown of your truck.

If there are any issues, refer to the vehicle’s service manual as fan clutch removal methods differ from application to application.

Diesel Components, Inc. provides heavy-duty Horton Fan Clutch and Horton Rebuild Kits at the best possible price in the market. We are one of a select few companies that Horton has authorized to distribute its line of fan clutches and engine cooling technology. Believe us when we tell you, Diesel Components is your best choice for Horton fan clutches.