Fujitsu AOT24PMAL Fault Codes

[johnmart]

Hi There.I have a AST24PBA with a AST24PMAL and it has gone on the blink.
The timer light is flashing and I was wondering if anyone had the relavent info as regrds what light sequence means what fault on the units.Any help would be appreciated.
John

[iceman007]

John

Do you have any fault codes? I assume the fan is not running and the timer is switched off. If you could give me a bit more information, I may be able to help you out. I'm usually working with either Mitsubishi, Daikin or Hitachi but I have Fujitsu manuals.

James

[johnmart]

John

Do you have any fault codes? I assume the fan is not running and the timer is switched off. If you could give me a bit more information, I may be able to help you out. I'm usually working with either Mitsubishi, Daikin or Hitachi but I have Fujitsu manuals.

James

Hi James,
The indoor unit is blowing slightly and then it shuts down completely the ops light blinks rapidly and the timer light flashes 13 times then has a short interval before repeating its 13 flashes.There is no start up fan in the outside unit (AOT24PMAL).Ihave no relevant info as regards this unit.

John

[Bones]

inverter model?

we had a similar problem with a 30 late last year, the inverter module shat itself in the outdoor unit... cant remember if the indoor fan was running or not, but from memory i'm pretty sure the lights were flashing like you mention.

easy to replace, its all un-plug plugin after you remove a few screws

have you tryed calling fujitsu technical support? some there guys here are fairly switched on - or have a computer program that spits out the answer from all the variables we give them.

[iceman007]

John

The model number you have is not available here. Possibly due to our lower ambient temps or something.

The problem you have is almost certain to be an electrical based fault. Bones may well be correct if he's worked on this particular model before. The only advice I can suggest is this- I have a friend working for Fujitsu technical but he's not 100% as he doesn't have manuals for that model number.

The first thing I would do is shut down the power completely to the units. Remove the wires from the compressor (make sure you make a note of where to reconnect them) Power it all back up again. If the fan starts up, then test the resistance across the compressor windings, and also make sure that none of the windings have gone to ground. If the fan shuts off after a short while, then you need to suspect something else.

This particular model, I know is inverter driven (I don't know how much you know about them). Basically, the inverter can vary the speed of the compressor motor, making the unit variable in it's capacity, altering this speed to match cooling or heating demand. Unlike the fixed capacity systems, they are much more efficient, as the compressor starts up not being under load and therefore draws less current. Typically the start up is at around 16Hz, with a maximum speed of around 116Hz(dependent on unit and make), but start up current is around only 3A or so.

The inverter works by taking AC and passing through a bridge rectifier to convert to DC. This is usually in the noise filter part of the unit, and consists of a diode stack and a couple of large capacitors, as the DC current is quite unstable and has to be smoothed out. Then this current passes through a transistor module and is switched to different sequences in a square wave voltage, which can control frequency, and therefore motor speed. If the inverter has failed, it must be replaced, but usually it's in 3 parts, the noise filter, reactor, and converter. Check there is a voltage present at the input and output to the noise filter, check the resistance in and out of the reactor winding, and make sure that there is voltage across the terminal wires to the compressor. It there is voltage into the compressor, then suspect this as the problem, but you should be able to isolate the problem and fix it.

If the model is a heat pump, you can check that the solenoid is energized here. There are variuos methods. Some techs at Hitachi etc will put the unit into heat mode and take the solenoid off. The unit should revert to cooling mode- this can help to identify if the valve is stuck, or alternatively stick the jaws of a clamp ammeter over and if the solenoid is energised you will get voltage.

Try these methods and let me know how you get on.
Good Luck

James


PS Check the pressures as well.

[johnmart]

Hi Guys
Many thanks for all the help .
After trying a new inverter unit and it still refusing to work the very kind people at Fujitsu sent me a whole complete outside unit and now we are all warm and cosy just in time for winter.Many thanks again

John