Why does my central air intake sound like it’s struggling even after replacing the filter multiple times and having regular maintenance?
Asked by Fatih Dağlaroğlu 
2 months ago
Last Updated: September 10, 2024
So, I’ve got central air in my house and lately, the AC intake has been making this weird hissing sound. It’s like it’s having trouble sucking in air, you know? I’ve changed the filter three times already, and each time it goes back to normal right away, but after a couple of weeks, it starts acting up again. The filter is clean, nothing in the house has changed. I have the roof AC unit serviced and cleaned every year, and it was just done a few months ago. Any thoughts on what might be causing this?
When was the last time you had the unit serviced, both inside and outside? Even with a clean filter, the fins need to be cleaned regularly.
I’ve found that cheap filters work best. Non-pleated ones are my go-to.
I mean, cheap filters are basically like having no filters at all.
And if there’s too much, the air conditioner can freeze up and the high limit can trip.
You know, it’s actually better for the system. Most systems are designed with filters in mind, so if you use a stricter filter, it might not work as effectively. But hey, what do I know?
It seems like there might be a low charge or dirty coil. Have they ever added refrigerant during a service or cleaned the indoor coil?
That’s exactly why it’s important to regularly change the filter.
It seems like you don’t possess a mechanical license. I’m not sure why you’re even bothering to comment on this page.
You’re on the DIY Home Projects page, silly boy!
The filter change seems to have resolved the issue. Is it noticeably dirty or filled with pet hair? Have you been running it for longer periods, since the fan-on time is a better indicator of filter use? Could construction or fry cooking be causing clogs in the fine filters? Or maybe the filter size is not suitable for the newer style filters due to old ducts.
It’s a good idea to clean the coils.
Make sure to inspect the air intake from outside that comes into the house.
Can you hear that ‘hissing’ sound for a while after the blower shuts off?
I’m assuming you’ve already checked for any obstructions in the vents or returns. Sometimes, even a piece of paper or plastic can cause issues. What’s the MERV rating of your filters? Most home systems can handle a MERV 8 without problems. If you’re using a higher rating like MERV 11 or 14 in a system made for MERV 8, it could be restricting airflow and causing issues. Try switching to a MERV 8 filter. If the problem persists, check the airflow and temperature coming out of the vents. If there are still issues, it might be related to the A coil in your ductwork. Consider calling a licensed HVAC service for further assistance. Good luck!
Hey everyone! I make sure to get my AC unit serviced every March – cleaned and tuned up. I’ve been using the same filters for 6 years. The unit starts making strange sounds about 2 weeks after a new filter. If I remove or replace the filter, the sound goes away. There hasn’t been any construction, and all the vents are in the ceiling so nothing could have fallen in. I also had the duct work cleaned about 6 months ago. It’s functioning fine, just a bit noisier. I’ll need to have someone come check it out 🙂
Ductwork collapsing