The law in many jurisdictions requires landlords to maintain rental dwellings in habitable condition. The term, habitable condition, generally implies basic necessities, i.e. doors that can be locked, water, heat, operable toilet plumbing. Legitimate habitability issues will not arise in a professionally managed apartment complex because maintenance will be prompt and adequate.

Habitability statutes allow a tenant to repair or replace some component of the apartment that is missing or inoperable if that component adversely affects habitability and if the landlord refuses to accomplish the necessary repair or replacement. For example, if the entrance door is broken, a condition that could clearly adversely affect the safety of the tenant, and the landlord refuses to remedy the problem, the tenant may have a legal right to have the door repaired or replaced at the tenant's expense and deduct the cost from a future rent payment. The habitability statute in your jurisdiction probably establishes a maximum dollar amount that a tenant may apply and it may be a relatively small amount, e.g. $500.

The habitability issue may arise in a well managed apartment complex because a tenant has an incorrect understanding of the habitability statute. The tenant may, for example, want an inoperable microwave oven replaced. If the tenant believes it will not be quickly replaced, the tenant may threaten to replace it and deduct the cost from a future rent payment. It is very probably the case that a court would not believe the microwave oven to be an item that adversely affects habitability.

The apartment manager has a responsibility to explain the issue to a tenant who threatens to misuse the habitability provision. The management company will insist on collecting the full rent amount if a tenant has misapplied the habitability provision and the company may or may not be inclined to reimburse the tenant. The tenant has no legal right to repair or replace a component of the apartment unless that component legitimately affects habitability adversely. It is better to prevent the problem than to deal with it after the fact.