Middle AC on 3990

[Boom]

Has anyone experienced the middle AC not hardly blowing air out of the vents? I had to replace several parts on this AC and got it back together finally and this is the first time it’s worked since I personally have owned it. So what it did before I do not know but what it’s not doing now I do know and it’s so bad I’ll bet it wouldn’t blow a feather away hardly. The air has to be going somewhere so any thoughts or ideas I would greatly appreciate. It’s too hot this year for this here in north Texas and I need to get it fixed. Thank you in advance for any responses and help!

[ATCguy]

If it's a ducted system (not direct)... then chances are your ductwork needs a good cleaning, and re-taping. Most of us experienced similar issues when new.

What's probably happening is that the bulk of your cold air is being directed into the cavity between the interior ceiling & the roof, due to shoddy workmanship at the factory. No only trash & debris inside the ductwork itself, but improperly taped outlets that allow the sir from the duct to escape into the cavity before reaching the vent.

This requires removing the interior vents, and then cleaning & re-taping all of your ducts. Also you'll probably want to climb up on the roof.. actually remove the AC unit, and then clean out the ductwork directly under the unit. Yes, it's a PITA chore... but many of us have found sawdust, clipped wire waste, and even soda cans in there.

Use the SEARCH button up above to bring up many previous posts on this subject, with instructions & photos of what probably needs done. Afterwards, and if it's not an issue with the AC unit itself, you'll be rewarded with MUCH BETTER airflow from your ceiling vents.

[dsol]

Also, does you unit have the vent directly underneath that allows the unit to dump all the air straight below? If you open that and it blows cold and with force then Tim will know it is the ducts themselves.

In my 3305 it is a two unit system and they are cross ducted so you get stronger air flow near the units themselves but even if only one is on you can still feel slight air flow at the other end. For instance if I run the unit over the main room I can feel air coming out in the front bedroom, but not real strong. When I turn on the bedroom unit then it obviously is much better in the bedroom.

[azdryheat]

Did you remove your middle a/c and look into the hole? My a/c was also not blowing well and it was because of shoddy workmanship. I have an old thread on it somewhere on this site. Anyway, when originally built, the worker didn't clean out the sawdust in the hole prior to applying the metallic tape to seal it up. The tape balled up and got stuck in one of the ducts and the cold air leaked into the ceiling. It was a quick fix for me to clean out the hole and re-tape it. That was 9 years ago and the a/c is still blowing nice.