Do you know how long the house has had a/c and heat? Most likely those were not installed until around the 1950's or later.

Since the air is filtered before going into the ducts, how much dirt do you think might have slipped thru and is resting in the ducts?

If you use a duct cleaning service, be sure they are good. Some make cleaning ducts a laughing joke.

My concern would be whether any of the duct connections have come loose, are still wrapped and whether they possibly are leaking air into the attic. A good check of the attic would be wise.

My suggestion would be to wipe as far as you can reach inside a ceiling duct with a clean cloth to see how much dirt you find.

thanks for the response.

I have heard that it is a waste of money, hardly anything in there. I would ask experts like a company that makes or installs duct work.

Another question. Is the ceiling dirty a few inches out around the a/c vents? If so, then the ducts may be dirty which would indicate the possibility of something being loose in the attic and sucking dirt into the system.

If the ceiling is not dirty around the vents, most likely you will find nothing in the vents.

The vents are close to the floor and no I don't see anything.

I had it done when we took possession of our current home and would recommend it. It completely refreshed the interior of the home.
I did see the collection receptacle before the job was done and it was clean- this is it after the ducts were cleaned.
It is FULL of dust, dirt bits, pet hair, and all sorts of assorted flotsam. I can't imagine living with someone else's filth if I can get rid of it for $400.

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That picture says it all. If there were pets in the house I would definitely have the ducts cleaned. Ask the new furnace installer about having the ducts cleaned and if recommended, before or after the installation. My daughter bought a house and did not have a home inspection. Imagine our surprise when someone reversed the ceiling fan, fur flying everywhere. I then checked the furnace filters, I don't think they had ever changed the filters.

If one is getting a new furnace and a/c new duct-work may be indicated. Our 1987 house did not have insulated duct-work and we had all replaced. Solves the old pet and dust problem as well as saves energy.

Air ducts cleaning is very essential for our home. First you need to decide your own air duct cleaning schedule because its effect our health also not many people realize that, the importance of air duct cleaning regularly to make sure superior indoor air quality. Our internal air quality can depreciate very badly with unattended air ducts.

Another thing to consider is that the old heating & cooling system was installed before Asbestos was outlawed. If there is any asbestos in the house there is no guarantee that a home inspector will catch it( unless he's Mike Holmes).They say that asbestos insulation is only a danger if you disturb it and the particles get dispered in the air.If you haven't purchased the house yet you could get that checked & use is in a price negotiation

If you dust the house & 48 hours later there is a coat of dust every where -- the ducts probably need to be cleaned . . . Good luck!

I had a problem with dust and had the ducts cleaned to the tune of >$600 which was the biggest waste of money ever! This company was recommended by our HVAC co. so you would think they were reputable. Never again.

My sister had it done and claimed it blew out more dirt/dust afterwards!