Rather than replacing your air conditioner ahead of time, let it run its course. They can last as long as 20 years.

Each year, thousands of Arizona residents email or call Rosie Romero’s radio show with questions about everything from preventing fires in their chimneys to getting rid of tree roots invading their sewer system. His goal is to provide answers that suit the specific lifestyle wherever someone lives in Arizona.

QUESTION: I recently heard someone on the radio talking about all the great new technology in air conditioning that will be on the market soon. I’ve been thinking recently about replacing my AC in the future, but I’m wondering if I should do it right now when the technology changes?

ANSWER: My opinion is that if your AC is running all well now, you should run it until it’s dead, rather than replacing it ahead of time just in case of a future breakdown. On the other hand, I do have to attest to the better efficiency of air conditioning over the past few years. A couple of years ago, I lost all my air conditioners and had to replace my roof because of damage in a hailstorm. I replaced 12-year-old AC units that probably could have kept running if they hadn’t been damaged. However, my cooling bill dropped 30 percent when I replaced them.

Q: We bought a house in June that has a huge scorpion problem. We’ve sprayed ourselves; we had a professional exterminator spray the house as well. But we just got back from vacation and we still have tons of scorpions, maybe 10 or 11 a day – some inside and some outside. So, should we have the house sealed? Is it worth the money?

A: Eleven scorpions a day is a ton. But it’s not unusual once you return from a vacation when your house was quiet and undisturbed to suddenly have a lot of scorpions. You might want to have another exterminator visit the house. You might also try sprinkling judicious amounts of diatomaceous earth around the entries to the house. But make sure that any sealing is done very carefully. There are weep screeds under the stucco, for example, that you don’t want to seal. But if you keep working on this issue, you will get on top of this problem.

Q: We recently had our roof repaired due to leaks that occurred in our hallway. Everything has been fixed, but now we still have stains in the ceiling of the hallway to clean up. Can we paint over them or does the drywall need to be replaced?

A: If the sheetrock didn’t swell up and wasn’t damaged, you probably don’t need to tear it out. Take an ice pick or pocketknife and test the stained area. Poke the area in the center of the stain and make sure there’s resistance to your knife. You don’t want the drywall to become mushy like a sponge.

If the area seems solid, you can treat the area first with water mixed with bleach and then brush on some paint that can stop mold before you repaint with your final color. If the stain is two to three feet wide, seal it with an area of the mold-stopping paint that’s two to three times bigger than the stain. That will prevent mold and keep the stained area from growing bigger if there’s ever another leak.

Q: How do we get rid of indoor gnats that seem to be breeding in our five houseplants?

A: You probably have fungus gnats breeding in the soil. You can stop them by spreading a thin layer of sand or diatomaceous earth over the top of the soil in the plants. That will kill the gnats. Or you can repot the plants in fresh soil. But you may be keeping the soil too moist, and should cut back on your watering. In fact, you might want to try all the above recommendations.

For more do-it-yourself tips, go to rosieonthehouse.com. An Arizona homebuilding and remodeling industry expert for 29 years, Rosie Romero is the host of the syndicated Saturday morning “Rosie on the House” radio program, heard locally from 8-11 a.m. on KNST-AM (790) in Tucson and from 9-11 a.m. on KGVY-AM (1080) and -FM (100.7) in Green Valley.