Changing air filters regularly will help keep air ducts clean. If ducts are dirty, hire a licensed air conditioning contractor to clean them.

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 systems. His goal is to provide answers that suit the specific lifestyle wherever someone lives in Arizona.

QUESTION: What should I do about hiring someone to clean my air ducts? What should I pay for the job? Many companies can charge as little as $30 to $40. I’ve never had the ducts cleaned in my house, but I did replace my air conditioner about two years ago.

ANSWER: You’ll see many duct-cleaning companies advertising that they will do a whole house for $79 or even less. But all they’re going to do is take a vacuum cleaner and reach as far as they can into the ducts with the vacuum hose. When they do that they are not really cleaning what needs to be cleaned. You want to hire a licensed air conditioning contractor who will take the AC cabinet apart to clean the coils and then put it all back together thoroughly, as well as cleaning the entire length of all the ducts. It should take them a day or two for each AC unit you might have.

Once it’s done, you don’t need to do it again for eight to 10 years, provided that you replace your air filters regularly.

Q: I own a 35-year-old patio home. Recently, my neighbor had a big clog in a sewer line that runs out to the road. The problem was apparently due to an invasion of roots of some trees from across the street. So should I pay a plumbing company to come in with a camera and check my pipeline to see if I have the same problem? And should I treat my sewer line with a plumbing compound that can kill roots?

A: It is probably worth trying and wouldn’t cost all that much to ensure that you don’t have the same backup problem developing in your pipes.

Q: I had a lot of mosquitoes visiting my home, yard and back porch this past summer. I kept trying to figure out where the water source was where they were breeding, but I couldn’t come up with anything. Do you have any ideas about solving this problem?

A: Usually the source is standing water from a water feature of some kind or a wet spot in a garden due to lots of irrigation. It might be in some neighbor’s yard. Meanwhile, you can plant certain scented plants to repel mosquitoes, like basil and citronella and rosemary and lavender. You can try burning citronella candles or use a fan to keep the air – and the mosquitoes – moving. Probably a combination of methods would help.

Q: I have a Joshua tree in my yard, and I’m wondering if it needs any special care.

A: It will need trimming from time to time, but you want to trim carefully in a way that the tree looks balanced. Not a lot of maintenance is required. If you manicure the old dry foliage in one spot, you might have to do it for the whole tree. Try to keep it looking as natural as possible.

Q: I’m digging a hole for a shade tree on a part of my yard that has western exposure. I want to put in a vertical type tree because I have a spot to fill that’s about 40 feet by 25 feet. Can I plant a pecan? Some people tell me they’ve lost a lot of them. So what should I plant?

A: Pecans are great when they’re established, and they’re very vertical trees. But they’re very thirsty and require a lot of water. You need to water the whole root ball. So plant the tree in well-drained soil and give the roots as much space as you can.

For more do-it-yourself tips, go to Rosie Romero, an Arizona home building and remodeling industry expert for 29 years, 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. Call 888-767-4348.