I live in mid Florida in a 1250 sq ft house that has one handler and one return vent. If I filter both vents it freezes up. So only one vent can be filtered at a time.

There is an air filter underneath the unit in the house 15x20x1 There is an air filter in the return 20x25x1 When we purchased the house there was only one filter, the return. I was told by our home inspector because it gets so Hot here that one filter will suffice. Otherwise it freezes up. Not enough air flow! My question is the return vent or air handler for a filter. I can’t do both!

Which should be filtered, Handler or return vent?

  • If your reference to "handler" is the output where the processed air comes out into the room, then a better name for that is possibly "outlet vent" or some such. The "handler" is commonly known as the blower fan inside the furnace or AC, or "air handler". Nov 28, 2023 at 17:46
  • "Supply". Why would you filter both? That's no different than installing two filters at one location.
    – isherwood
    Nov 28, 2023 at 19:52

1 Answer 1


HVAC setups usually only have filters on the return vent side, right behind the AC blower/furnace. The output vents are unrestricted.

The freeze-up could be from not enough air getting through due to two filters being wrongly used.

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