GE Arctica refrigerator/top freezer

Freezer keeps defrosting/melts down, probably 3 x per week.
when it kicks back in, freezes quickly.
Have done the following:
- vacuumed and blew out coil.
this seemed to work, but it did melt down a few days after doing this.
wondering if unplugging and plugging back in had more to do with
'fixing' the unit than blowing out coil
- pulled off panel from inside freezer to check freeze up on the fins - negative
- no waterline or ice maker attached.
- right now, as i open freezer door can hear no sound whatsoever, so can't tell if fan and/or condenser is running. they both work, just intermittently as the unit does re-freeze.

at this point do i purchase a new one or is this an easy enough fix to warrant a repair?