Changing both controller and inverter PCB assemblies

Your assistance please.

I was recently advised by an electrical contractor specialising in aircon that the reason my fujitsu AOTS12LDC inverter unit was not working was because the pcb needed replacing - quotes on the way! I've just looked again at the job sheet and realised the engineer/technician is looking at replacing both the controller pcb and the inverter pcb.

My initial question is, is it usual for both to be replaced in this manner. During the visit he took the top off the indoor bedroom unit (and had a quick look in) and went outside too look at the outdoor unit (did nothing more outdoors than write serial numbers down).

?

OK,
Let me ask you a question.

My car mechanic have told me that he want to change both the engine and the left rear tyre, is that normal?

As you can see, without enough information we can all come to the strangest of conclusions.

What is the problem with your unit?
How old is it?
Any fault codes?
What is the cost for an engineer to attend your house versus the cost of the PCBs? You might find that the cost for the PCBs is less than the cost for an engineer to attend therefore if it is a communication issue it might be cheaper to replace both PCBs than to get one and then have to return on a separate occasion to replace the other...

:cool:

G'day.

In my experience the indoor PCB (controller PCB as you've called it) doesn't normally go down, more common is a comms error due to a faulty outdoor PCB and/or fan motor.
Diagnosing that lot isn't a 5 minute job, unless you're a flying Kiwi. :-)

Cheers,
Andy.

Valid point!
It's a comms fault.
just 6 years old and out of it's 5 year warranty.
Had a quote from the firm that came out and had a look - PCBs are coming in at c$390 (indoor PCB) and $560 inverter PCB) exlusive of labour..................total $1,300 !!!

Hi

Yeah its a comms fault and the firm has decided to replace both PCBs - the quote is $1300 all up (indoor PCB $400 and inverter $580 exclusive of labour..........

You're in Oz, so there's a good chance it got Gecko'd. Or destroyed by other vermin.
Also, it's a Fujitsu.
The last but two that I worked on, a gecko had suicided across the inverter outputs. Once you see that, it's easy. Check the compressor is electrically ok. If so, replace the inverter card & quite likely the main card too.
As I recall, on this occasion the boss had been the first attendee & Funitsu tech. support (henceforward FTS) reckoned it was the indoor card, which he duly replaced with no change in the fault. I got sent with an outdoor card which FTS had suggested, but the wrong one had been picked by their spares dept. So while I was there, I got onto FTS & did more diagnostics (I also had our inverter checker with me). The result of that was all outdoor cards to be replaced.
On that unit, you couldn't see behind the IPM, so it wasn't until I went back with the new cards that the reason for the fault was found to be a gecko.
Now, if I suspected a 'gecko fault' I'd just order all the outdoor cards & have done with it.

I should mention that FTS are usually excellent.