i also regret choosing Pana air-cond.. i'm not using those econ navi series though..

but the previous ones..
i've been using them for the past 4 yrs...

all were ok, until they get noisy after regular services...
the noisiest ones are located in my bedroom and dining area.. 

those are the most used ones lah... both also 2.5HP
the others, smaller HP ones, still ok... not noisy YET... 
for sure, the next time i want to buy, i'll choose another brand, either Daikin or York...

no more Panasonic ...

Some people also mentioned that York is noisy.....

If suddenly got ice flying out.. small Pierce ice flying when I sleep in midnight just now..Panasonic 1.0 inverter. Seem alot problem...I buying time after 1 month then problem come...aircond with fresh hot air coming out.. then they come fix and after few month now got ice come out..

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Added on July 22, 2012, 5:58 amIf suddenly got ice flying out.. small Pierce ice flying when I sleep in midnight just now..Panasonic 1.0 inverter. Seem alot problem...I buying time after 1 month then problem come...aircond with fresh hot air coming out.. then they come fix and after few month now got ice come out..

Check if you have enough refrigerant/ leakage. Check also if you have dirty indoor unit coil.

Same problem, newer Pana model. I'm not sure what the "sound" you have is, but for me (I don't reco this as a long-term  solution ), a hard knock with my hand on the side (NOT the front) solved it, i.e. there was a loose or vibrating part somewhere. Grease won't help, get someone to check it part by part.

PS, a lot of people have the view that Panasonic products now are much lower in quality than they were many years ago. My old National fan, 20 years and still perfect working condition.