First week on a 793F fleet, I stopped a high-temp derate by washing the coolers and confirming fan clutch engagement with a strobe after spotting 105 C converter temps five minutes into a ramp pull. For folks just jumping in, what’s your go-to start-of-shift check — mine is a quick look at cooler cores and a thermal scan of hub bearings, because 20 F deltas show up before the noise does.
I keep a strip of flagging tape in my pocket and do a 10-second airflow check at the cooler face before the first ramp; if it flicks forward, a dust curtain or shroud gap is letting hot air recirc and you’ll be staring at “105 C converter” again even with clean cores. In high wind it lies, so I confirm with a quick IR shot across the fan door seam.
On 793Fs my first minute is cracking the surge tank cap cold, then bumping to 1200 RPM and feeling the top hose — if it doesn’t go rock hard, I replace the cap and clear the bleed line before I chase the ‘fan clutch’ or cooler face. That simple check has fixed two early derates that mimicked airflow issues. Caveat: crack the cap slow in case someone topped it hot.