Strange fault

[Aardvark]

I've been out to a Klimair split unit that someone has already been to a few days ago. The guy changed the indoor unit fan motor thinking it to be faulty but the unit still wouldn't run. I have since been called to look at it and my first thought was that the pcb was faulty. Klimair is a generic OEM from china and has the same origin as Dalco units for which i have spares. I fitted a new PCB and then when i put the power on again i got a buzing noise from the indoor fan motor, when i turned the unit on the motor got quieter but didn't run until i gave it some assistance. I removed the motor from the pcb and plugged in the old motor (un-fitted), as soon as i applied power to the unit the motor started to run even before pressing "on". I have now tried 2 different boards and get the same result when the unit is back together. Buzzing when power is applied then quieter when the "on" button is pressed but have to give the blades a little flick to get it spinning. Oh and there is nothing restricting the motor bearing or fan blades.
Any suggestions would be most helpfull

[airefresco]

Is there an external capacitor for the fan?

[Aardvark]

there's a cap on the pcb but i thought the likely hood that 3 different boards having 3 knackered caps was a long shot, the 2 i had on the van are both new

[momo]

Is the motor speed controlled by an AC triac? Or by a set of relays? What you could be having is a leak through noise suppression capacitors in parallel with the triac - just sufficient to rotate a no load motor!!

[Aardvark]

It's a basic chinease split mate. On the PCB is 1 1.5micro farrad cap which starts the indoor fan motor.

[monkey spanners]

Live and neutral round the right way? Have seen some odd things happen when they aren't.
One time was due to the main incoming cables in the fuse box being wrong.

Jon :)

[Aardvark]

yep all wiring correct, unit has been in the premises for some 5 years, another engineer looked at it before me and replaced the motor then when he had the same result told them to buy a new unit. Then they called us, i went out to look and tested the old motor which he'd left behind and it works fine. I replaced the PCB and had the same fault which is why i'm puzzeled, tried another PCB after and have the same thing. So the basics are - indoor fan motor won't run but it's had a new motor and pcb?? there's nothing else that can interfere with this function?

[Yuri B.]

Suggestions:
1. Just for any case - brown wire of the supply cable is fed from the live, and blue wire receives neutral?
2. Is the connector from the fan put in the right slot on the pcb, and if in the right slot, is it inserted the right way ?
Check as well the condenser's real capacitance.

[Aardvark]

all cables/plugs are in correctly

[fridge doctor]

Jono,

Can you rule out under voltage? If that is OK then what about the motor the other guy fitted... is it identical to the original. If the 3 way mains connector is configured differently (or even wire coloured differenty) to the original, then that would account for it's reluctance to start and the buzzing noise. (You did mention that the old motor appears to run OK) Also, did the guy fit a new motor? If it was a 'reclaim' the bearings could be shot and have enough end play for the windings to act as a solenoid and pull the shaft (and blade) back within the motor housing and effectively remove the free play in the blade and cause it to jam. Check for excessive end play.

Put the old motor back into the housing properly and try it again with your new PCB, even though you say that (as a free air test) it started before pressing the 'on' button, you might be mistaken. I know what the conditions here do to your mind Jono, don't forget that many systems will start up on their previous settings when the mains is re-instated, could you have overlooked that on a day of up to 40 degrees?

Regards, Trevor

[Aardvark]

haha tell me about it!!lol i'll try it Trevor and see what i get but these machines are the same as the parent for the OEM Dalco and they don't have auto re-start, plus it was a spare Dalco board i fitted. Same sh*t different name :D

[fridge doctor]

"it was a spare Dalco board i fitted." Oh bugger !!

I had a spare board from Dalco in Limassol... they sent me two, both quite obviously repaired and asked me to 'take my pick' What can I say !!

[Aardvark]

sorry jus to close this thread. result was another new board and another new motor. Lovely