Fuji split stopped working AOTR12LCC

[Bustedfuji]

Hi all,

I’m a bit of an hvac newbie but I’ve done a bit of general purpose fixing on a broad array of stuff. My Fujitsu split has apparently stopped working. It was last used prior to being professionally cleaned and prior to some substantial rain.

It has now stopped working properly, it will turn on briefly, and run the outdoor fan for a very short period. Relays make some audible clicks before the power to the outdoor unit is cut.

The indoor unit flashes green 3 times with the red operation light staying off indefinitely.

I’ve checked the 3 connections at both the indoor and outdoor unit and they seemed ok. I’ve cleaned the wires and reassembled. The outdoor live and neutral lines read 243v for a short period, and spike to 500 odd before going to zero when it shuts down.

I had a quick look at the circuit board and couldn’t see any fried components or burst capacitors or obvious shorts. The fuses measure continuity.

I measured across the thermistors and they read as follows
Cn70 thermistor
10.3k

Cn71 thermistor
3.2/6.7

Does anyone have any pointers to work out what’s wrong?

[Peter_1]

You have to count how many times the red and thereafter the green light flashes...this is the error code.

[Tayters]

Here's a link to a manual. It's the UK version but probably not much difference:
https://www.manualslib.com/manual/1126312/Fujitsu-Asya12lcc.html


That's a comms error, something has happened to the outdoor unit and the PCB isn't powering up or perhaps in your case losing power somehow.

Testing can be awkward as outdoor gets voltage supply from indoors and when there is a fault the indoor relay drops out so testing outside gets tricky.

Outdoor gets powered from a relay on the indoor unit so you are saying it spikes to 500V? That means power supply to indoor is the same but that can't be right.
Anyhow if the outdoor fan runs up then it looks like the compressor starts and that's when it faults. Test compressor winding for continuity and megger to earth, should be a good start.

Cheers,
Andy.

[Bustedfuji]

Thanks for the manual and advice

I think the 500v is like a kickback spike or something along those lines as it is only for a second or something. Maybe from the fan or a cap dumping backwards?

The supply to the unit is definitely 240v from the wall. More like 237 actually.

Unfortunately I don’t have a megger, just a multimeter.

Based on the diagram, it sounds like I should see continuity between w7/8/9?

Ie should I see continuity between w7 & w8 or w8 & w9?

Is there a starting capacitor that can be replaced? Any idea what part number might work?

[Tayters]

It's an inverter setup for the compressor so it's a star wound 3 phase winding.
Just measure between each winding and they should be an ohm or two.
Check this inverter test guide I posted a few years back to check the PCB side of things: https://www.refrigeration-engineer.com/forums/showthread.php?37273-Inverter-Testing&highlight=inverter+testing


No capacitors for the fan motor either, that's a BLDC variety so if it spins up then all good otherwise they are pretty good at flashing the relevant fault code.
As an experiment you could try running with fan and/or compressor disconnected. Be careful to power down for a couple of minutes before unplugging the fan motor or testing any of the inverter parts on the PCB.

Cheers,
Andy.

[Bustedfuji]

I haven’t been able to check yet due to the inclement weather. If unplugging the compressor lets it stay on for a little longer or changes the error message, what’s likely wrong?

Low lube? Low gas? Replace compressor?

If it gets to compressor replacement it’s probably going to be logical to just replace the whole unit.