Ceiling Cassette Heat Pump Line Set Noises

[gansh62]

I have a 36,000 btu mini split system (LG) that works with ceiling cassettes (4 of them). I'm getting a weird noise from the cassette units. It sounds like the system is sucking Freon through the line sets. When this occurs, all of the ceiling cassettes have the same symptoms and it gets quite loud (wakes me up at night). MY HVAC tech doesn't know what it is. Any ideas?

 

[Phuckin' Jim]

Normal sounds while defrosting.

 

[gmcgeo]

sounds like it is defrosting

 

[Jim greengo]

Does it do it all of the time?
Restriction in line or metering device?

 

[Slednut]

Yep, they make a different sound while defrosting, when our Mitsubishi's did it I was a little curious but didn't really worry about it. I installed a Mr Cool last summer and it has a df on the display when it makes the noise.

 

[gansh62]

Does it do it all of the time?
Restriction in line or metering device?

Thanks for the question. It does it periodically during the day and night. At times it is extremely loud and will wake me up. Really strange if this is normal. I'm not sure if there is a restriction, but I'll ask my HVAC tech to check it out...he's a heat pump expert but has limited experience with ceiling cassettes. Maybe its an issue with the branch box, because all of the units make the noise at the same time.

 

[gmcgeo]

Thanks for the question. It does it periodically during the day and night. At times it is extremely loud and will wake me up. Really strange if this is normal. I'm not sure if there is a restriction, but I'll ask my HVAC tech to check it out...he's a heat pump expert but has limited experience with ceiling cassettes. Maybe its an issue with the branch box, because all of the units make the noise at the same time.

Does it make this noise in AC mode?

 

[gansh62]

Does it make this noise in AC mode?

It makes the noise in both heat and a/c modes

 

[TRITOON]

my heat pump only makes the noise during heat mode, at first it worried me, but it just last about 5 seconds and i think its in part due to the 2 story rise from the floor level to second floor.

 

[yeldogt]

With multi mini-splits there is always some refrigerant flowing to all the heads -- you can hear it occasionally ... but it should not be loud

 

[LS6 Tommy]

It makes the noise in both heat and a/c modes

The linesets are resonating something. I bet they either secured them too tightly or didn't use good tubing mounts that isolate vibration.

Tommy

 

[gansh62]

Tommy, I don't think its a vibration. The noise is like a sucking sound, like sucking liquid through a straw when you get to the bottom of the cup...almost like there is no freon in the lines. My HVAC tech just came by to see if freon was low, and it wasn't. Weird and fristrating.

 

[gmcgeo]

• Swooshing, crackling or gurgling: This can take place if your mini-split turns on defrost mode to keep itself from freezing over.

if your mini-split keeps turning on defrost mode, it’s a hint that something is off, such as low refrigerant, a bad circuit board or malfunctioning sensors. Your AZ Air Conditioning and Heating HVAC tech will be able to locate and correct the problem rapidly.