Main PCB replacement for Fujitsu aou24rlxfz or just buy a new outdoor unit

rsel04

Hi, I've had a Fujitsu mini-split system installed for a number of years. One of my outdoor units is indicating a serial communication error based on the blinking light sequence. I removed the cover from the the outdoor unit and saw that there is what looks like a burn mark on the PCB which leads me to conclude that the board is toast. Have not had much luck sourcing a replacement board. The model number is AOU24RLXFZ. Since this unit is already quite old and sourcing replacement parts is a challenge, does it make more sense to replace the outdoor unit with a newer model and if so, is it possible to hook up the existing hoses and indoor units to a different make/model? I'm not sure if just replacing the outdoor unit is possible.

GGross

I don't have access to the Fujitsu compatibility tables, maybe someone here does and would know? For the brands I sell the old boards are surprisingly inexpensive, many times there are compatibility issues though with newer outdoor units and older indoor units. Have you tried going through a Fujitsu dealer to get a proper diagnosis? I would be surprised if they don't have parts available for it

pecmsg

IF the board is no longer made then the entire system gets replaced. Contact Fujitsu tech support for board availability. 

rsel04

Thanks for the replies. Will give Fujitsu a call tomorrow.

SuperTech

rsel04 said:

Thanks for the replies. Will give Fujitsu a call tomorrow.

Good luck, I hope you don't have to wait on hold as long as I usually do with them. I'm familiar with the unit you mentioned. If it's the inverter board and it's not under warranty I wouldn't attempt to repair it. I firmly believe that the Fujitsu engineers designed the unit to make it as difficult as possible to repair.  Replacing the boards on those units was one of the most aggravating jobs I have ever done. 

I would also recommend taking a good look at the indoor unit. The blower wheels tend to accumulate a fuzzy black moldy looking growth and of course they are very difficult to remove and clean. 

I'm sure you paid good money for your system but unfortunately it was designed to be disposable and only last as long as the warranty period.

Put your resources towards a better system.  Mitsubishi units tend to be designed better and are usually easier to work on.

rsel04

Thanks for the details. I would really like to avoid replacing the indoor units and all the connections if I can so I might just stick with Fujitsu. This unit lasted a good number of years so if I can replace it with a new one and have it last as long as the current unit I think its money well spent. I see that they went ahead and rebranded the Halcyon line to Airstage. Do you know if its just a name change or are there other differences. I'll ask Fujitsu as well but if the wait times are as long as you say, I may get an answer here before I get it from them.

STEVEusaPA

Here’s how it’s going to go.
When you do get them on the phone you will need to provide them with indoor and outdoor model numbers and serial numbers.
Then they’ll have you ohm out a number of things to see if other components failed/needs to be replaced.
If it’s just the board and you don’t know why it fried, it would probably happen again. So you wasted a lot of time and money you could have just put into a new system with a warranty.

rsel04

Sounds like fun. All I need to know is whether or not my indoor units will be compatible with the new outdoor unit. Based on the feedback here, I think I'll give up on replacing the board. I'm assuming if I stick with the same brand and zones it should work but would want to be sure before I pull the trigger on a new unit.

EBEBRATT-Ed

And if you just replace the condensing unit what do you do next year when the indoor unit quits?

rsel04

Well, I guess that's when I'll replace the indoor unit. I have 7 indoor units in total. Are you suggesting I should replace them all because the PCB board fried on the outdoor unit?

STEVEusaPA

rsel04 said:

Well, I guess that's when I'll replace the indoor unit. I have 7 indoor units in total. Are you suggesting I should replace them all because the PCB board fried on the outdoor unit?

I’d think in your case I’d probably try a new board but really try to figure out why it fried. Tech support should walk you through all the checks with your meter. Why they won’t publish these secret ohm readings on their app or in the I/O manual is another issue.
I’m sure they would tell you which outdoor unit would be a suitable replacement if that’s the way you have to go.

SuperTech

In my experience their tech support will have you ohm out the compressor, condenser fan motor, electronic expansion valves and if they test ok then it's usually a new inverter board, control board and active filter module. Sometimes they throw a condenser fan motor at it too, even if it ohms out ok. It's hit or miss with their tech support guys. Some of them really seem like they don't know much. 

Good luck with it.  Prepare yourself for a frustrating experience. 

pecmsg

rsel04 said:

Well, I guess that's when I'll replace the indoor unit. I have 7 indoor units in total. Are you suggesting I should replace them all because the PCB board fried on the outdoor unit?

Exactly why you don't do with that combination. 2 or 3 indoor units to each outdoor unit. WHEN something fails you have some systems operational.

rsel04

Yes. That's the configuration I have. 3 outdoor units and 7 indoor units. 2-3 indoor/outdoor. I just don't understand why I would change any of the indoor units if the problem seems to clearly be a bad pcb on the outdoor unit unless its possible that one of my indoor units caused the failure of the outdoor unit.

SuperTech

rsel04 said:

Yes. That's the configuration I have. 3 outdoor units and 7 indoor units. 2-3 indoor/outdoor. I just don't understand why I would change any of the indoor units if the problem seems to clearly be a bad pcb on the outdoor unit unless its possible that one of my indoor units caused the failure of the outdoor unit.

Because there's a very good chance the indoor units are in poor condition and extremely dirty at that age. Unless you have been religious about having them deep cleaned on a regular basis. And there's a good chance that the indoor units are no longer compatible with the new outdoor units. I've seen that with Fujitsu systems that weren't as old as yours.

pecmsg

rsel04 said:

Yes. That's the configuration I have. 3 outdoor units and 7 indoor units. 2-3 indoor/outdoor. I just don't understand why I would change any of the indoor units if the problem seems to clearly be a bad pcb on the outdoor unit unless its possible that one of my indoor units caused the failure of the outdoor unit.

About every 5 - 7 years the computers advance so much that the old models just aren’t worth upgrading. Everything gets replaced. 

It’s minis. There disposable!

GGross

I would personally investigate a new board before resorting to replacing everything entirely. Between a fujitsu dealer and tech they will know if the board is available, or the new unit would be compatible with old heads. I had compatibility issues in the past but the top lines have got better about this over the last decade.

rsel04

Thanks. I checked with Fujitsu and the new units are the same as the units I have. Even same model numbers. Just rebranded to Airstage. They also confirmed my indoor units are compatible. I see no reason to swap out indoor units that are working perfectly well. The logic that they should be swapped out just due to age does not make sense to me if they are still working. Thanks everyone for your input and advice. I will go ahead and investigate a new board and failing that will swap out the outdoor unit for a new one of the same model which should make installation fairly straight forward.