When fixing the refrigerator, refer to the user manual.

Literal

Refrigerator [object-を] fix [if-なら] instruction-manual [object-を] refer-to [imperative].

Uses 参照する ('to refer to, consult'), a slightly more technical/document-oriented verb than the synonymous 参考にする. Also notice 取り扱い (with okurigana) vs 取扱い (without) — both are accepted spellings.