Hi HVAC exeperts,
Looking for your expert advice on this AC behavior.
My home is 1 year old and the home inspector identified AC supply and return ducts interchanged in Master Bedroom, Laundry, and Master bath. I have communicated the issue to AC company as the unit is under warranty. They have interchanged ducts and after, we were experienced slow cooling and the second-floor thermostat never hits 72 degrees and keep on running. I have called the AC company several times as the machine keeps on running and all the time the company tried to educate me that it is all because of ambient temperature, wall radiates heat etc. They said according to Manual J if the home cools 25-degree difference that ambient temperature would be enough.
Before the duct switch the home cools relatively fast but now each one-degree drop take 60-75 minutes and when it closer to 72 degrees it takes 2 hours or more, mostly don’t shut off.
I have a doubt that whether supply and return air mixed together as I see a lot of carpets dust accumulated in various places which we don’t see this before. Is there any chance that this could happen? If so how could this will be identified?
So could you please advise how to identify the root cause of the issue as the AC company said everything is perfect which is really not.
What are the potential reasons do you think the system is running like this?
I have observed that when they switched the duct, the return duct is placed on top of the supply duct.
Please help as I am not an HVAC expert.