What can wait, and what cannot?
The purchase decision may allow time to compare options if the home can be used safely without that furnace. That is different from continuing to heat with it. Ask the technician what restriction applies now and what evidence is needed to resolve any dispute about the diagnosis.
If you want a second opinion, get the report and images first, and share them with an evaluator familiar with the model. Keep the restriction in place during that review. A second opinion should address the original finding, not simply report that warm air comes from the vents.
Make the waiting plan concrete
We recommend comparing the supported repair with replacement, then making a separate plan for the period without furnace use. Ask about part availability, the full repair price, what condition remains in the rest of the furnace, and what a replacement includes. Request actual dates or an identified next update, rather than choosing from an uncertain estimate.
For interim comfort, ask the involved professionals what arrangements are appropriate for the home and household. Do not use an oven or range to heat the house. CDC specifically warns against that practice. CDC carbon monoxide guidance.
Consider whether the home remains suitable for everyone staying there while heat is unavailable. If it does not, arranging another place to stay can be part of the plan. Do not let the calendar become the only reason for accepting unsafe use.
Your next step is to confirm the written use restriction and compare the complete work options. Waiting to buy and continuing to run are separate choices. Only qualified clearance can answer the latter.