Fujitsu AOU36RML issue

[jtdon99]

Discovered this site while searching for service diagrams for a Fujitsu AOU36RML split system with 3 indoor wall units. Woke up the other morning to no AC, the outside breaker on the unit was tripped.
I reset it and used a remote to start one of the wall units, it came on and started flashing the timer light 2x every 15 or so seconds. I looked that up as serial comm. error, went outside took covers off of electronics and started looking and searching web and etc. I found a post here about a gentleman in Hawaii whose system fried a gecko, I live in Hawaii but found no geckos cooking in the unit. I did find a bad Active Filter Module (I've attached a jpg that shows 2 holes blown in it, with matching carbon marks on the cover). I found a Service Instruction manual online for my unit and it said if the Active Filter Module tested bad to replace it. I checked it and got bad results on most of it. My concern is this- since I did not observe any other damage should I just replace it or is there a good chance something else caused it to blowup ? I was an electrician in the Navy some fifty years ago and can make good use of my multi-meter but I am not familiar with AC units. Any advice would be greatly appreciated, living here on a fixed income can be tough with the prices we pay for services here. Thank You Jim Donovan

[monkey spanners]

Its difficult to tell, most of the diagnosis on mini splits seems to be changing parts till it works, even when directed by the manufacturers technical guys.

[oneshot]

As you posted this in November I am probably a little late but I just had a supposed professional come out and service my unit and the active filter module looked a lot like yours.

The “professional” changed the board but did not check anything else first before firing it up and it popped both 30 amp fuses. He then changed the control board and the power supply board.

On the control board the bridge rectifier that provided the DC input for the active filter board all four terminals were shorted thereby sending AC line Voltage to the active filter board rather than the rectified DC voltage it was supposed to be receiving. How the filter board did not fry again is a mystery to me. I am sure however that its service life has been shortened.

Long story short at a minimum check the bridge rectifier on the control board before you put in another active filter board and fire the system up.

Just follow the terminals on the active filter board that are marked (+) & (-) and they will lead right back to that rectifier.