Fujitsu AOT45LJBYL Ducted system tripping breaker?

[alan_man]

Hi guys, got a call from the sister in law saying her Fujitsu ducted system was tripping the circuit breaker on heating mode after approximately 15-20 mins after operation. It was installed about 2 years ago and had no prior issues at all. CB is rated at 32A. I don't deal with ducted systems but figured I'd go past for a quick look to try find any obvious issues. First thing I thought I'd test was how much current the unit was actually drawing. Set the temp on the control to maximum then headed out to the switch board with my clamp meter. Current gradually ramped up to a steady 24A which I figured to be high since the rating on the spec sticker states running current on heating to be 16A. As luck would have it the breaker did not trip while I was there (was there for around 20 mins) but I also noticed the breaker to be quite fragile it self (would not reset properly and would flick off manually very easy). Other than this there did not seem to be any obvious issues (no odd compressor noise etc) Does this running current seem to be high indicating some compressor issue? I don't plan to look into it much further as it really is Fujitsu's issue now however I'm still curious to know, thanks in advance

[moondawn]

usually the main thing to take a circuit breaker out is the compressor, perhaps when the temp of the compressor gets too hot it draws too much current and then trip.

cheers lee

[monkey spanners]

If its a fixed speed compressor it could be a failing capacitor amongst other things.

[paul_h]

Inverters always draw more current than what's on the label, especially flat out on heat.
I would suspect it to be more like 20A though, but maybe higher current draw possible if poor airflow through the indoor as well as high load required from the system.
Would really need to know pressures. ie if HP pressure not that high, then there may be a problem with the inverter or compressor, but if HP pressure really high, then would need to check air flow.
Could be a dodgey C/B or bad wiring connection to it, was the c/b hot?

[nike123]

Change MCB and see if happening again.

[alan_man]

Thanks for replies, I got her to clean the air return filter the night she called which apparently was filthy, she did this but to no avail. It did trip once after that but apparently has not done it lately which is odd. The CB did seem dodgy (although not hot when I was testing amp draw) so I was going to change that first to see if it fixes things before she has to run around chasing tails calling the installer/Fujitsu. I am not planning to touch anything else JUST incase Fujitsu try turn around and say the machine has been tampered with. I will let you know how it goes, thanks again to all

[nike123]

Also, you should check for correct air flow at heat exchanger. It may be dirty no matter of filter.

[stufus]

Is it the right type of breaker ? Motor rated?
Obviously at 24A you are 1.5 X's nominal heating rating of 16A but the breaker is 32A .Seem's a bit on the big side.
Apart from that like the others I'd check the air flow across the indoor coil.
Cheers
Stu