Chip for identification- I hope

[Turnip]

Hi folks,

Like some others, try mend most anything that comes my way. Currently have a heap of Carver caravan (electric/gas) heaters to fettle. Problem is usually the under-rated darlington that drives the fan going O/C, or our electrician brothers getting supply polarity wrong on test and burning print on the controller.

Got one where fan runs all the time. system uses 2 PIC procs and a chip I can't identify. It's marked as-
358 (at the top) then ST-A605 underneath. Can't find it anywhere - any thoughts ? - Chris.