First thing’s first, check your lease! Generally speaking, unless the damage is caused by the negligence of the tenant (tenant action or inaction), responsibility to make major repairs such as heat, air conditioning, electric, plumbing is that of the landlord. Minor inexpensive items are the responsibility of the tenant.  Wis. Stat. 704.07(1) and (2).  The landlord’s promise to repair must be in writing and have a completion date if it is made prior to the lease being signed. The landlord is also required to notify the tenant in writing of unavoidable delays which make the completion of the repairs impossible to complete prior to the initial promised date. A completion date has to be given in any case. ATCP 134.07.