In the household folder that’s labeled “Guarantees, Warranties and Instructions,” I recently found guarantees and warranties for two Walkmen, three combination locks I may have used for high school PE, a Smith-Corona typewriter, the Minolta 35 mm camera that was stolen when we were in Paris, the belt for a London Fog raincoat and the set of silverware we got when we were married that we left at our friend Norman’s house when we still knew Norman.

There were also instructions on how to operate the bathroom scale (Step 1: Step on it. Step 2: Deny) in case we had forgotten.

I didn’t find, however, what I was looking for: the warranty on our HVAC system.

HVAC, apparently, is an acronym that stands for Home Valuables Aren’t Close. I wasn’t close to finding it.

The warranty for the system wasn’t filed under H, nor was it filed under Systems. It wasn’t there under cooling and it wasn’t under heating. We couldn’t find it under “Important Documents,” either, nor could we find it where you would normally most expect it, in our file of New York City subway maps.

I was looking for the HVAC warranty because, with the first warm day of the spring, the first day of air conditioning wasn’t conditioning the air. At first, I assumed, of course, that this was because I didn’t know how to operate the thermostat. My wife has been trying to teach me how to operate it for five years. But, you know, it’s complicated.

You have to make split-second decisions about whether you want to program a scheduled override or access humidity display. Should the fan be on automatic or just “on,” and really, what’s the difference anyway? If you put the system on “Aux Heat” what happens if you don’t have any auxes? And is it still the same temperature if you use centigrade instead of Fahrenheit?

In the absence of the warranty, and the absence of the air conditioning, we called the repair company. The repair guy came out and immediately diagnosed the problem: the HVAC system was broken. He immediately diagnosed the solution, too: Money, lots of money.

But fortunately, he told us, the system should still be under warranty, assuming we could find the warranty.

My wife looked in the usual places — the cookie jar, the bathroom medicine cabinet, the pile of newspapers by the side of the bed. I tackled the kitchen cupboard, the trunk of the Subaru and the pile of newspapers on the other side of the bed.

No luck.

Finally, we had the brilliant idea of looking in the folder we have kept in sight for 12 years, mostly on the dining table, that says, right there on the top, in large, bold letters: HVAC Warranty.

The warranty was there. It had expired last week.