Fujitsu AOT45 Split Ducted PCB ISSUES

[bobby 14]

Hi guys i am currently working on a Fujitsu AOT45 Split ducted a/c unit. We have had a power spike with no spike protection that has knocked out 4 of the same units, units have had new indoor filter modules as that appeared the problem although has not fixed it. Terminal 3 which is the control has correct voltage of modulating 70-95VAC when disconnected although has 220VAC coming from indoor PCBoard just wondering if anyone has come across this or a similar issue and what the end result was. Have had fujitsu down and followed instructions which has not fixed problem

[Ontherun]

G'day Bobby14, New to site and never posted anything in my life, so hope this makes sense. I don't have a solution to your probem unfortunately. I have have just looked at an AOT45LJBYL which had stopped working after a power spike. The 3.15A fuse(F2) on the main control board outside was blown also there was a darkened patch in the same area close to that on the board but not black. A resistor in the same area tests open circuit. I have replaced the board and still have error (E01 Communication error indoor and outdoor). The indoor fan runs but nothing else. I am presuming the error code will disappear when the fault is fixed. I have not seen anywhere on how to delete or reset it. I will have to do further testing to see if there is another board gone or other reason. Will let you know how I go.

[Robin]

240v steady on the indoor serial cable means damage to the chip. Assuming a power surge or similar you may have a situation where the 2 PCBs in the indoor unit are damaged & it may be if you replace one only the other will damage the new board. Suggest you replace both indoor boards on one unit & see how it goes.

[paul_h]

The only way to test fujis properly is make up a multimeter handle with a 600V diode inline for the positive multimeter lead.
When testing putting the MM in dc volts, the negative lead on neutral the diode lead on the signal, should give a 20-55V reading for the indoor signal.
Then put the positive indoor diode filtered lead on the neutral and the MM neg lead on the signal for the outdoor board signal which should be again 20-55v dc fluctuating.
That gets rid of any induced voltage or boards putting out high voltage which can happen if you are just checking signal to neutral with normal multimeter leads.
As you can tell by those readings I've said though, when connected, the signal should by 50-110 v AC.
The diode fitted to the positive MM probe just makes it easy when checking DC volts as to which board (indoor or outdoor) is faulty without disconnecting anything.

[Ontherun]

Has anyone got the service manual for the AOT45LJBYL? I already have the parts breakdown and circuit diagrams.

[paul_h]

Yeah, are you in the trade or one of those that sells manuals online or fake parts sites?