Mitsubishi Mini Split Head loud clicking

Robert_H

I was doing a cleaning service on a Mitsubishi mini split system and the owner pointed out that one of the heads will make a loud "Snap" during the night. The timing seems random but happens even with the head off (system on). it is particularly troublesome because it trigger his dog. even if the dog is in a different room.

The problem was addressed in February by a Mitsubishi Elite contractor that replaced the POWER P.C. BOARD, which reduced the noise frequency buy %80, by the customers estimate. but it still exists.

The customer recorded audio overnight and extracted this clip. I would describe what I hear as a knock then a loud snap, and then the knock again. The snap sounds like a contactor to me. listen to the attached file please.

https://www.dropbox.com/scl/fi/sejz6g6czxg54cn4r4cj7/sound-clip-of-click.mp3?rlkey=0v4av3c486sr6zuievken2i8n&st=k57svnsp&dl=0

The Heads is MSZ-GL12NA manufactured in 2017 part of a two head system using a branch box.

Also, the head has an older drain pan safety switch I have not seen before instead of interrupting power or communications, it interrupts one of the coil thermistor wires. strange to me…

pecmsg

expansion contraction

Robert_H

what is expanding and Contracting? I've installed a lot of Mini Splits and I've also cleaned a lot of heads and fixed a few here and there. I have never heard of this happening. If the head were starting up and shutting down I could see maybe there would be some expansion and contraction. But this is with the system off at random times during the night.

pecmsg

the copper tubing through the galv sides.
how oversized is this head?

Steve214

Check for miswired head A to B instead of A to A.