Fujitsu AOT36RBAL fan fault !

[hitmanzak]

Hi all
well decided to help a mate out and do a repair on his ducted AC system. Called round today thinking nice easy job, how wrong could I be....
complaint was no cooling, popped gauges on 10bar standing, 32 deg ambient, and switched unit on, out door unit fired up and watched the pressures run low for few minutes, checked inside and fan not running.
Switched unit in to fan only high speed, fan eventually kicked in at low speed !
history is the fan sometimes runs in high, may start to run in cooling then switch off, won't work correctly in fan mode.
Struggled to get through the loft cursing, swearing and sweating f...ing 52deg up there, no lights, nothing to crawl on, rubbish every where, not happy...
cant really get to the electrics but managed to pull the capacitor off and take reading of 3.1 mf, electrical diagram says 4.0 mf.
No faults showing on display!

I am going back in a couple days when they take a few roof tiles off for access, my question is what's the best way to diagnose this, thought it was a sensor on the indoor coil at first but the motor is playing up in fan mode. Obviously I don't want to go changing PCB, motors, sensors just to "hope" it may fix this, oh and it's a mate too.
AC is not my line so any one with similar problems please feel free to share.
Give me a chiller any day...

thanks guys

[hitmanzak]

Spoke with Fujitsu technical today who have told me the unit is too old to order spares even if I wanted !
Is this normal for manufactures in Australia to stop spare parts availability after 10 years old ?
Surely there must be some thing out there with out have to rip this out and fit new, any ideas guys ?

[ozairman]

I know this is late but I dont come here often are you in Australia or the UK, your profile says UK but you describe an Australian model? if you are in Aus then please read on what model is the Indoor unit exactly? For that model outdoor there was a real Fujitsu indoor unit ART36RLAH and an "Aussie" made abomination with a model something like CDS/CDW36R. The fan decks on the Aussie made ones can be replaced with something out of the Actrol catalogue with a bit of bodging.

However dodgy fan control means the first place to start checking is the fan speed relay wiring and make sure that the wires are all on the right terminals as per the diagram and not mixed up, one relay switches low speed and the second one switches medium and high and there is a third relay (an SSR) that starts and stops the fan motor. The SSR's sometimes fail and they go into a partially shorted state but the symptom of that is normally an indoor fan motor that does not stop when the unit is turned off at the wall controller ,it continues to run at a very low speed as its getting fed one half of an AC sinewave through the SSR. If they are left in that state too long then they tend to burn out the Indoor fan motor :(
Anyway hope this helps a bit.

[r.bartlett]

I know this is late but I dont come here often are you in Australia or the UK, your profile says UK but you describe an Australian model?

.

Here is a clue as to the original posters location:

http://uk.weather.com/story/news/032613_uk_outlook-20130326

[hitmanzak]

Hi Ozairman, thanks for the advice... When we got the tiles off the roof a couple a weeks back it was found to be the fan motor. Got a new motor from Heat Kraft and bench tested it so all ready to fit, hopefully next week. Tested all the speed signals from the relays and found all good. My only concern is no fault codes were picked up from the sensors when the fan motor had stopped and the outdoor running and eventually cycling on/off L.P. Is this normal for an old Fuji system ?
By the way it was an abomination CDW36R and I live in South Australia.

[ozairman]

My only concern is no fault codes were picked up from the sensors when the fan motor had stopped and the outdoor running and eventually cycling on/off L.P. Is this normal for an old Fuji system ?
By the way it was an abomination CDW36R and I live in South Australia.

I'm sorry to disappoint you but they don't even have an LP switch in them only a HP switch! Fujitsu started out making wall mounted split systems before venturing into larger products so their control logic is similar to how most split systems work. They have anti frost protection which looks at the temperature of the indoor coil, if it gets below 5°C it kicks the indoor fan speed up by one step (if it's not on high already). If it's on high and if it drops below 2°C the compressor is stopped. Once the coil warms up to above 6°C and the 3 minute minimum off time has passed then it restarts. Most of the error codes on those units relate to sensor open or short circuit errors, except high discharge temp and HP error.
Sorry about the abomination comment, the CDW fan coils were not the best match with the Fujitsu outdoor units they did not heat that well.
The last thing to watch out for on these systems was dodgy soft states in the outdoor unit that would overheat and lock out on hot days, but most of them would have been weeded out by now.

[hitmanzak]

I'm sorry to disappoint you but they don't even have an LP switch in them only a HP switch! Fujitsu started out making wall mounted split systems before venturing into larger products so their control logic is similar to how most split systems work. They have anti frost protection which looks at the temperature of the indoor coil, if it gets below 5°C it kicks the indoor fan speed up by one step (if it's not on high already). If it's on high and if it drops below 2°C the compressor is stopped. Once the coil warms up to above 6°C and the 3 minute minimum off time has passed then it restarts. Most of the error codes on those units relate to sensor open or short circuit errors, except high discharge temp and HP error.


Thanks for some unknown useful information mate, very interesting. I guess my outdoor unit was cycling off on the froststat.
Any way i have told my mate to save up for a new one, thanks for the information ozairman mate.
Where in oz are you fella ?

[assailant]

I live in South Australia.

update your location in your forum profile.. it helps give us more context to your problem!

[hitmanzak]

update your location in your forum profile.. it helps give us more context to your problem!
Yeah, tried that..... Won't let me edit the location, any ideas ?