Panasonic Air Conditioner fan repair?

[aargee]

We have a Panasonic CK-E21 split system air conditioner that works fine except for the fan in the outdoor unit. After 20-30 mins it starts to squeal and the fan slows to the point where the unit overheats and stops (summer here in Australia).
So, it appears the bearing(s) is stuffed.
AC guys came and told me as much for $165 and then a few days later advise that the fan is no longer available and the only option (for them) is to replace the whole AC for thousands of dollars.

I'm going to have a go at dismantling the fan and replacing the bearings, the only other options are to find a salvage unit or retrofit another brand fan with a rigged up interface to the original circuit.
Nothing to lose in trying.

Question: anyone else with experience in this with any constructive advice?

[amyk]

It sounds like the bearings need some lubrication.

[orbiter]

If the fan/motor is stopping and the thing is not clogged up, it sounds like the bearings are history. Standard ball and roller type bearings are not normally that
expensive so assuming the AC unit readily comes apart replacing the bearings should hopefully not be too difficult..

Hopefully the bearings will come out cleanly for you otherwise you may need a puller etc to remove the old bearings, especially if they've been cooked onto
their shafts or into their housings.

I had a similar bearing problem with a washing machine not too long ago, unfortunately though the bearing was part of the drum and another drum was half the price of a new machine

[gadget73]

If its ball bearings, you can likely get new ones easy enough.  Most bearings are an industry standard type, and you can cross the number to get one from anyone.  If its a bronze sleeve bearing, those can require some other work.  If its not too bad, you might just be able to soak fresh oil into the felt after cleaning the inside of the bearing and shaft off.  If its really cooked on, I've had some success in heating the old bearings to cook out old oil, then submerging them in fresh oil and applying vacuum to re-impregnate them.  Usually around a 10 weight oil works pretty nicely for this.  I've used engine oil as well, and it also works out OK.


Surprised they can't fit some sort of universal replacement type fan motor.   This isn't rocket surgery, its just a simple electric motor that needs a shaft of the right size and shape and appropriate mounting hardware.  Unless your central AC stuff down there is grossly different than ours here, it should just run off mains power and probably it mounts using a couple of studs sticking out of the back into a bracket.

[bills]

It appears that it could be a dc condenser fan motor as they used both depending on model. here is a link to a E21 service manual.
http://www.kaelte-bast.de/dateien/pana/th/2008/sm_cs-e21.24.28hke.pdf
hope this helps.

[aargee]

Thanks all,

I have removed the fan and can access the bearings -but- they seem to be moving quite freely (and are difficult to remove).
I'm wondering now if it is the drive circuitry in the motor, the noise was only starting after about 30-40 mins (chirp chirp noise) and gets pretty bad within 5 minutes (constant squeal), until the fan slows to a crawl then stops. If left, the AC then shuts down due to overheating.
Cycling power and it goes for another 30-40 mins (sometimes more) quite normally.
I'm wondering if the CPU is putting the fan into a low power mode and the controller electronics is having a dummy spit.
I would have thought a bearing is bad, and that's it. Bearings are shielded 608Z type, few drops machine oil has not changed the behaviour.
Doesn't seem repeatably related to temperature. The motor body gets to mid-40s (deg Celsius) in about 15-20 mins and stays there. Tonight after cycling power it ran happily for an hour and a half before I turned it off, with no hint of a problem.

I might pull the logic board (not easy to do) and check for high ESR caps as well...

[orbiter]

When the fan next stops after it's 30-40 mins .. See if you can turn the fan easily by hand. If so this will help rule out
tight/failing bearings, and point more towards an electrical or motor/capacitor issue.

[bills]

Is the motor ac or dc ?
If it's a ac motor check the motor run cap.

[aargee]

Fan spins freely, can't believe it's a mech issue.

It's a DC control, from what I can see. Magnet is the rotor with a wound stator controlled by a reasonably complex circuit (hidden at the back of the motor housing).

From memory (at work now), the wiring from the control board to the motor -  there are 4-5 wires running to the motor. PWM control from the CPU, and an interrupt, two supply voltages plus ground. Next step to try and induce the fault and meter/CRO the voltages.

Luckily I have another identical unit to compare with.

[station240]

Sounds like it's a BLDC motor (brushless DC), with the usual switching devices and hall effect sensor based feedback.
Perhaps it's simply a bad solder joint in the PCB stuck to the back of the motor.