If it’s been a while since your last air duct cleaning, you’re probably tempted to make that call and get someone in your home to sanitize those ducts that promise to deliver cool air throughout your home this spring and summer.

But before you do, you’ve got to arm yourself with some knowledge to avoid falling prey to an air duct cleaning scam!

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6 things you need to know before having an air duct cleaning

We consulted an expert to learn about the warning signs and caveats you need to know…

Beware of carpet cleaners pulling double duty as duct cleaners

Here’s a classic upsell from carpet cleaners: They get in your home to work on your carpets and then offer to clean your air ducts, too, for a rock-bottom price.

Don’t take the bait!

"This is maybe one of the biggest scams — carpet cleaning companies that say they can clean your air ducts for $49.99, then they remove and vacuum your registers, stick their vacuums into the duct at the register, then re-attach your registers,' Dave Baker of WSB's Home Fix-It Show tells Clark.com.

A thorough duct cleaning shouldn’t be treated as add-on service to a carpet cleaning. Expect to pay several hundred dollars — up to somewhere in the neighborhood of $500 — and be ready for the job to take at least two to four hours to complete.

If you want to find reputable companies for duct cleaning, check with the industry organization National Air Duct Cleaners Association.

Know when a duct cleaning is necessary and when it isn’t

Baker recommends an immediate duct cleaning when you move into a newly built home.

‘There’s lots of construction debris. Saw dust, dry wall scraps [and even] Doritos bags can end up in the duct work of a newly built home,’ he says.

After that, Baker says a duct cleaning should be done every 7-10 years — unless you have someone in the house with breathing problems.

If that’s the case, then Baker advises a different route. “You should get your HVAC provider out to your house to upgrade your furnace filtration situation. That is money better spent than on a yearly or every two year duct cleaning scam.”

Make sure your HVAC system will be cleaned too

“A quality duct cleaning isn’t, in my opinion, complete without your HVAC system cleaned at the same time,” Baker says.

But here’s the thing: Duct cleaners aren’t legally allowed to touch your HVAC unless they have a current HVAC license.

The company must provide you with the license number upon request. If they can’t or won’t, that’s not a good sign.

While we're on the topic of HVACs and dust, most HVAC maintenance plans include regular changes of the furnace filter. But changing the filter between visits yourself — usually every three months — will help keep your system running at peak efficiency and cut down on dust.

How to change your HVAC furnace filter

Not sure how to change your HVAC furnace filter? The first thing to do is remove the existing filter from your furnace and make a note of the size that will be printed on the sides of the filter. It will be something like ’14x25x1′ or something similar. Remember to put the filter back when you’re done.

Next, head to the store or look online for a replacement filter. You can get a good one for anywhere from $5 to $20 at a big-box store like Walmart or Target or at the home improvement stores such as Home Depot or Lowe’s. Your local supermarket may even carry filters in limited sizes, but the prices will often be higher here than at other places.

If you're noticing a lot of dust or other allergens in your home, it may well be worth it to pay the few extra bucks to get a filter with a higher Minimum Efficiency Reporting Value (MERV) rating. MERV ratings are on a scale from 1 to 16 for most residential uses.

Once you've got your new filter, you're ready to take out the old one and put in the new one. We've got a DIY video here to guide you through the simple process.

Good companies will pay attention to this extra

“A quality duct cleaning company will and should clean your dryer vents too,” Baker says. “They are also ducts!”

Beware of unsolicited pitches

Here’s how this one works: A company calls you and says that they will be in your neighborhood next week and can clean your ducts for $25 or some other outlandishly low price.

Baker isn’t buying it. “This has so many issues with it just on the surface — you can’t even get a pizza delivered to your house for $25 for one thing — that it screams SCAM!”

The home fix-it expert has received these calls himself and here’s what he discovered after trying to set up an appointment:

“I pressed the lady [on the phone] the last time [they called] and told her I was interested. I agreed to set up an appointment, [then] asked for a number to call and after much back and forth she gave me [a bogus] 555 number. We never did hook up.”

Push back on the mold scare tactic

Companies that put a mold test kit in your house and hope the test results will prove that you need your ducts cleaned are likely just scaring you.

If you’re told you have a mold problem by a duct-cleaning company, Baker recommends buying your own test kit at a home improvement store to independently verify what they’re saying.

But there is an additional caveat here.

“Every decent mold test kit will detect mold in every house every time because there is mold in the air everywhere, unless you live in a hospital. So you can’t just go by the findings of a store-bought mold test to determine if your house has a serious mold problem,” Baker notes.

“Mold isn’t the only reason to clean your duct work though. [Ducts] do get dirty over time and can lead to having more dust in your home. Dust is just a fact of life, as everything emits dust.”

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