I have a 3-zone HVAC. All 3 zones a/c worked fine until recently. Now, in the morning, before it gets too hot, all zones still work fine. But in the afternoon, when it gets hot, the a/c to zone 2 stops working, while the other zones continue to work fine. When zone 2 is on in the afternoon, the evaporator unit is running, but no air is being pushed out of the vents.
If it was a frozen evaporator coil, shouldn't all zones stop working? If it was a damper issue, shouldn't zone 2 not work during any part of the day?
I'm at a loss, any help is appreciated. Thanks.