You said it yourself, it’s not working properly. These landlords will tell you to turn on the oven and leave the door open for heat while they’re comfortable at home taking your money. If they’re hurting because you need a repair they need to reevaluate their life choices and probably pick up a second jobs

For real though. It’s not working right then it’s broken. You aren’t getting full heat therefore the furnace isn’t working correctly and if the furnace is not working correctly then it is in fact not working, regardless at what capacity if it is fully working it isn’t fully working.

I don’t doubt there will be a minor disagreement when it’s all said and done but you have the law on your side. You’re paying the repair yourself, the same way as if the landlord would have paid it.

NOW saying that I almost guarantee you that the landlord will hit you some bs like “I could have gotten it done cheaper I won’t accept that.” Tell him to get bent and he should have taken care of it when you first said something. At this point get a lawyer. The cost for the lawyer will be repaid if this gets dragged out. If it does drag out withhold rent in a escrow account at your bank/credit union. Nothing will hurt more than “nonpayment” don’t let them fool you though the escrow hold is more than legal. Don’t sign anything from the landlord from the repair point on without a lawyer.