Daikin outdoor unit squealing and screeching when finishing a heating cycle

Forums › Home Workshop DIY › Daikin outdoor unit squealing and screeching when finishing a heating cycle - anyone else have this?

timmmay

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#319426 23-Apr-2025 22:05

Occasionally our Daikin Ducted outdoor unit makes a weird squealing / screeching noise for 10 - 30 seconds when it's finishing heating and is about to turn the outdoor unit off. I uploaded a recording here. It was recorded in the wind and then noise reduction applied, so it sounds a bit muted compared with the actual sound - it sounds sharper and louder in person.

Our first ducted system outdoor unit did this. Eventually the supplied replaced the outdoor unit, they said the problem was too difficult to diagnose and fix on-site. I'll email them about it again.

Has anyone else heard an outdoor unit make this sort of noise?

tweake

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#3366989 24-Apr-2025 09:52

does it sound like liquid or metallic?

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timmmay

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#3367042 24-Apr-2025 10:31

Metallic. It almost sounds like metal on metal at times. It also sounds a bit like gas being forced somewhere at times.

johno1234

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#3367101 24-Apr-2025 11:02

Sounds like the hamsters need feeding.

HowickDota

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#3367103 24-Apr-2025 11:10

Could be from the inverter drive ramping down, is the compressor/fan motor still running at that point? Also the expansion valve might be closing as well which would explain the refrigerant sound

timmmay

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#3370395 4-May-2025 18:49

Has anyone else heard anything like this noise from their heat pump, when it's in heating mode but just finishing a heating cycle? Our installers says they can come and have a look at it, but if they can't find a fault they will charge us $200 for the visit.

Last time this noise happened they came out a few times and couldn't find the problem, but eventually they replaced the outdoor unit to fix it. It could cost us the better part of $1K for them to say "nah it's fine" if it takes a few visits.

mentalinc

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#3370396 4-May-2025 19:28

Can you create a video of it with your phone and send it to the installer to see where the sound could be coming from.

Should help them understand what or where the noise is from, and have the go a yup thats abc and easy fix.

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tweake

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#3370397 4-May-2025 19:29

got a model number? it would be interesting to see what refrigeration circuit they use.

google shows it may use an electronic expansion valve and there's a few comments they get sticky. i wonder if its not closing fully on shut off and your hearing gas squeal as it goes through. thats a wild guess but if you can get it to do it and try to pinpoint where the sound comes from.

timmmay

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#3370402 4-May-2025 20:46

It's a Daikin FDYAN85A-CV.

This noise happens occasionally - might be once a day, might be once a week, might be a few times a day, we don't know. Because it's still fairly rare it's very difficult to capture. The installer has no interest in a video, they said the only option is for them to come and look at it, which is reasonable enough, I just don't want to be charged over and over again if they can't find a problem.

Right now I'm just trying to work out if it's a normal noise. My assumption is it's not a normal noise, given last time it was happening they replaced the whole outdoor unit.