Fuse 24 blowing intermittently
 

Hi Everyone
Brother in Laws 2007 F350 converted from Australian Ambulance to Ute. Fuse 24 has started blowing after 2 years and happens randomly. Sometimes good, sometimes fuse blows 2-3 times a day. It affects ABS, Speedo, Aircon & Blinkers. Earthed correctly. Triggers randomly whether air con is on or not as I thought may be the aircon clutch was causing it. Fan blower on dashboard not performing as it was, so I was wondering if it was on the way out and possibly feeding back on it itself electrically? i Any ideas guys? I am open to any ideas!

As you are aware a fuse will blow when current demand exceeds the fuse rating.. From what you describe, the blower motor is suspect. Usually when blower speed drops from good performance to less, with the same speed selected, If it not part of an automatic system, usually indicates the blower motor is pulling an excessive amount of current usually caused by dry bearings. This can be confirmed by placing an amp meter in series with the blower motor when high speed is selected and if the current (amp rdg) exceeds the rating of the fuse , the fuse opens and does it's job of protecting the circuit from excessive current draw which can result in burned wires/components
You can either have someone with a meter confirm that or just replace the blower motor.