carrier split indoor fan speed low

[bangoman]

this unit is a high wall split indoor model 1C-841591KG7A.
fault:fan motor nt blowin enough smetimes just slows down on its own.

remedy:
changed capacitor ----- no change
changed remote reciever pc board ------no change
this attempts done by other techs so far

my diagnosis
checked resistance of the windings:
r -b =5.6
r-o=4.5
o-b=1
r-red
b-black
o-orange
motor ok windings resistance balanced
there is another set of wires fro the motor to the pc board(indoor) labelled hall rpm snsor .
I suspect the pc board might be faulty nt takin rite signal
Can I go ahead n change the pc board ??
hw does this hall rpm sensor work .
the motor is a psc i guess

[paul_h]

Hall sensors detect a break in a magnetic field, ie if you have a plate with a slot cut out of the edge, a hall sensor mounted near the edge could detect the slot cut and know how many rpms the plate is spinning. So the hall sensor is inside the motor.
Cars with a distributor but electronic ignition use a hall sensor to fire the ignition coil.

I take it you are testing the fan speed in fan only or cool mode, so the evap temp isn't limiting the speed in heat or auto mode?
Did you check how much voltage is at the fan plug?
If there's 240v there I'd suspect the motor.
If there's not full voltage there, I'd suspect the PCB.
If not sure, I'd say 80% PCB, 20% motor.
Motors aren't expensive, less than the cost of a callback and further stuffing about

[bangoman]

thanxs paul,fan motor was replaced by another tech so pcb left.So wats the purpose of hall sensors in arconditioners

[paul_h]

thanxs paul,fan motor was replaced by another tech so pcb left.So wats the purpose of hall sensors in arconditioners
They pulse the motor in some circumstances, ie before heat starts, or in auto mode etc, so they want to know the fan speed.

[nike123]

Check that correct wiring has done when fan has previously changed. Trace from PCB.
On orange you should have neutral (common).
On black you should have phase from solid state relay.
On red you should have phase from fan condenser.
If hall is wrong then you will probably have error announcement on LED-s.
These fan behavior i found when fan leads are interchanged between start and run windings. Also, fan is rotating backwards and overheating, if that is the case.
By the way, that was cause of my troubles in this thread (http://www.refrigeration-engineer.com/forums/showthread.php?t=12282&highlight=fujitsu+strange).

[bangoman]

indoor unit is 42100g fixed speed splits . the wires bn traced .ol ok no risk of miswiring the fan checked volt to fan motor ol ok

[nike123]

indoor unit is 42100g fixed speed splits . the wires bn traced .ol ok no risk of miswiring the fan checked volt to fan motor ol ok

When fan slows down do you have also voltage drop from PCB?

[bangoman]

Ddnt check wen it last dd. Thing its intermittently so nt ol the time does it slow dwn