High EOT

Does anyone out there know if the fan clutch engagement has anything to do with the A/C being on or off?

I am experiencing high EOT's. My fan clutch will engage but cycles on and off at about 3-5 second intervals. I even have the blue wire mod switch to engage my fan full time and it still cycles on and off. The fan does not seem to come on nearly as frequently when the A/C is turned off. In fact, When the EOT is hot, I can turn the A/C on and off and the fan clutch corresponds by turning on and off - WTF?

I also wonder if it could have something to do with the EGR valve.

I've been working on this problem now for over a year. It's frustrating as hell! I would appreciate any insight.

Thanks,

John

Recent repairs:
New fan clutch
New ford thermostat
New EGR cooler
New oil cooler
Removed and cleaned radiator
Flushed coolant
New IPR valve

Mods:
None - bone stock with 185K miles