*
Husky Energy unexpectedly shut down an isocrackerunit at its 177,000 bpd refinery in Lima, Ohio, on Monday toconduct repairs ahead of the summer season, according to asource familiar with the refinery's operations.
* The repairs are expected to take a "few weeks" and have animpact on production rates, the source said.
* The refiner is also running less heavy crude afterrecently cutting rates to coker due to furnace issues, thesource said, adding rates will likely increase by next week.
(Reporting by Jarrett Renshaw, editing by G Crosse)