Originally Posted by PSDx3

2002, F250, 7.3PSD, 100K miles The fan was cycling on/off all the time, sometimes for just a few seconds. Replaced the clutch unit and now it almost never shuts off. Never had this problem with any of my Powerstrokes. The temperature runs normal all the time. Anybody have an idea what is going on?

Originally Posted by 64F260

On the 203 stat thread, one guy had pics of a lot of dirt and debris blocking up the flow of air through his condensor and radiator. Hard to see it unless you remove it. This may be causing your fan to run too much?

Originally Posted by danskool

...This help? found this out of my Service Manual ...Fan Clutch Test

Spin the fan blade (8600) by hand. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Fan Clutch Test—Minimum Speed Requirement
Use a suitable marker to mark the water pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).
Connect a tachometer to the engine.
Install a throttle adjusting tool.
Connect the Digital Photoelectric Tachometer.
WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation.

Start the engine and run it at approximately 1,500 rpm until the normal operating temperature has been achieved.
Operate the strobe light at 4,320 rpm for 5.4L and 6.8L engines and 3600 rpm for 7.3L diesel engines, and aim it at the water pump pulley. Adjust the engine speed until the light flash and the water pump pulley mark are synchronized.
Aim the strobe light at the fan blade bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade bolt (the fan blade appears to stand still).
The fan blade speed must not be greater than 1,900 rpm on 5.4L engines and 2,000 rpm on 6.8L and 7.3L engines.
Turn the engine off.
If the fan blade speed was greater than 1,900 rpm (on 5.4L) (on diesel engines and 6.8L, 2,000 rpm), install a new fan clutch (8A616).

Fan Clutch Test—Maximum Speed Requirement
Perform Steps 1 through 5 of the Fan Clutch Test—Minimum Speed Requirement.
NOTE: The temperature of the air hitting the fan clutch should be above 96°C (205°F) for maximum fan speed.

Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200). This will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.
Place the climate control function selector switch in the MAX A/C position and the blower motor switch in the HI position.
Adjust the strobe to 4,320 rpm for 5.4L and 6.8L engines and 3,600 rpm for 7.3L diesel engines.
WARNING: To avoid the possibility of personal injury or damage to the vehicle, do not operate the engine until the fan blade has been first examined for possible cracks and separation.

Start the engine and adjust the engine speed until the strobe light flash and the water pump pulley mark are synchronized.
Aim the strobe light at the fan blade retaining bolts. Adjust the strobe light until the light flash is synchronized with the marked fan blade bolt (the fan blade appears to stand still).
If the fan blade speed is less than 3,600 rpm on 5.4L engines and 3,500 rpm on 6.8L engines, 2,850 rpm on 7.3L engines, install a new fan clutch.

Originally Posted by schlepprock250

I'm just shooting from the hip here,but could it be the A/C high pressure switch?I don't know if these are like big trucks but with a big truck when the A/C is on the fan stays on.

Originally Posted by canister

That's some great information. How bad is it to drive the truck with the fan always running? Will it hurt anything? Whats a new fan clutch usually cost?

Originally Posted by Kwikkordead

Ed has them for $342.06

www.partsguyed.com