There was a bulletin about adding suppressors when you had Car Light and Fan Shutdown relay, CLFS. They would be located behind main swing panel , on horizontal terminal strip ( of you have tall cabinet)

If this is the issue you should be able to inject high the I/O for CLFS ,or the I/O that controls controller fans- FAN. Not sure if you have IMS available.

Knowing that it only happens when running further confirms noise. Maybe just start replacing suppressors anyway, pn# 9804420. I pretty sure CLFS feature doesn't activate when on inspection.