hi, my civic 1994 sohc non vtec d15b2 is drinking water fom the expansion tank next to rad and sometimes it chucks all water back out so the expansion tank gets full and overflows. i have been told its a problem with matrix fan behind the dash. heaters work fine

i have done compression check on cylinders and seem fine.
also changed radiator and cap and thermostat. bleeded and flushed rad.

any help. thanks