Mitsubishi Electric Zen - Loud Noise in Heating Mode

Hi,

Well I eventually had my air conditioning unit installed.

All working fine in cooling mode but after my installer went, I thought I'd but on heating mode. After a few minutes, there is a tapping/catching noise from the indoor unit which gets increasingly loud and not normal.

It seems to come from the middle of the unit and sounds like the rotating fan is catching on something. When you turn off fearing it is going to fall apart, as the fan slows down the tapping frequency decreases.

I'm guessing it is one for Mitsubishi but as I bought the unit myself and got a local refrigeration guy to fit it, I'll probably have some push back on the warranty.

As anyone else experienced this situation

Obviously fed up, nothing seems to go to plan.

Many thanks,

Damian

put it in fan only mode , with the louvres set on a fixed position, change fan speed to see if the noise changes to prove its the fan- its difficult to cause fan motor/scroll damage- is the wall its fixed to flat- is the wall bracket secure- difficult to check, is there a condensate pump behind it- could be priming itself- if its gravity drain then ignore that idea, is the unit secured to the wall plate properly (are the 2 lugs under the fan clipped into the back plate?
has your installer identified the issue?- if youve bought the unit the warranty is with yourself- so any parts you need to order , would be charged for then the faulty part inspected and if deemed faulty then you would get a credit

have you over lagged it- the pipework under the unit that was brazed- have you run it along the bottom of the unit- if its too bulky then it can distort the unit

Pretty certain it's secured to the wall properly, it does sit a few mm of the wall I noticed but assume this is the design to help deal with none flat walls.

No noise in cooling mode. Could well be over lagged. As I was stressing about getting sufficient insulation on the pipes running along the back of the unit, we actually managed to fit 9mm thick Armaflex tube on them, rather than a couple of wraps of 3mm thick tape. Seem to push on the bracket ok. I did notice that the noise got slightly worse if you pushed lightly on the unit.

in heating mode the fan will run at low speed, when the outdoor starts up the coil temp will rise to 30 deg- during this process the coil will expand and you will get a clicking noise, but if you say pushing against the unit makes it worse then maybe reroute the interconnect cable or run the drain hose from the left hand side of the drip tray- might be easier to remove the outer insulation on the drain, carefully slice the outer plastic coating and unwrap the thin layer of foam

Drain is already taken from the left side.

It looks a bit awkward to unclip but I will do so and test if it works ok when not fully engaged on the bracket. If this us the problem, I will look if the cable is contributing. Failing that, I will need to do something with the lagging, either try and get a better fit in the void or cut off and wrap with a tape and a smaller wall. Pain in the backside either way.

Thanks for your comments, appreciated as ever.

to unclick the bottom of the unit- look for 2 tiny little triangles on the bottom of the unit- you need to pull down there- use a bent brazing rod- if you can clip out the bottom right corner where the electrics are- then you can prise it down with your fingers on the right hand side- left side is trickier- might be easier to cut a hole in the plasterboard -as you wont see it when the unit is back in situ- be careful not to lift the unit off the top of the bracket otherwise its squeeky bum time!;)

Ok got the unit away from the wall and in certain positions the noise goes away but it can be still there when away from the lagging.

On further inspection, it Looks like some of the plastic at the back of the unit as melted and warped when being braised. My guess is that this may have meant that the plastic is slightly protrudingon the other side where the fan is rotating.

Just trying to work out how to get the vanes off as per the instructions to see if I can see or feel anything inside.

You couldn't make it up - not sure where to go with this. Supply and install next time, not that this time is right.

pitfall off choppin off flares- makes it easier to install but harder to get off the wall to replace- the plastic housing behind the fan scroll is the main part of the wall mount- (everything else fits to it) if you can see where its catching on the fan, cheapest option is to get a chisel in or a file to try and remove the excess build up

http://files.sotmarket.ru/instr/komu...msz-ef-0-1.pdf
service manual for indoor;)

I think I am a little closer to working this out.

Now that there front panel is off when you look down at the unit from above, it looks like the plastic back has warped out and is touching the heating coils (it is above the area where the brazing took place). When I push it away from the coils, the noise stops, so it is a vibration thing. I'm not sure if the fan is catching this area also, it is difficult to tell as it will be up at the back of the unit.

It looks there show be a few mm gap between the plastic and the coils. The attached picture of the area and the adjoining area will hopefully help explain.

I'm thinking would a piece of armacell tape stuck on the plastic act a a dampener. It is going to be difficult to get a file down there to take some of the plastic away. Any other ideas.

Nothing ever seems to go right at the moment, but appreciate your input.

Attachment 11754

Attachment 11755

ia the plastic fan scroll ok?- switch off the unit you can carefully open the louvres (both hands at each end) and rotate the fan slowly to ensure the impellor isnt warped

It seems ok, there is no sound when I rotate. I managed to get a thin piece of cardboard and was able to slide it up around the back of the impellor without it getting stuck on anything.

I'm not 100% certain though as the sound earlier was very much as if the impellor was catching on something, rather than a vibration further up.

I need to get a powerful flashlight and try and get a mirror up there. If it I'd warped up the top, it will be warped further down. Can the impellors be removed?

Interestingly the noise has only briefly occurred since I removed the panel cover but it obviously still lurking!

dont ask about removing an impellor- pain in the ass- you mentioned if you pushed 1 side the noise stopped, what if you pull the unit away from the wall on the opposite side- get a big flat screwdriver- to act as a spacer between the unit and the wall- then if you can stop the noise, then you can pack it with say the mrs credit cards- cut em up and pack it out- good luck

Hi, I'm not sure it is anything to do with the unit on the bracket, I was still getting the noise when I brought it away from the lagging.

I rear plastic back is definatley warped forward which is either catching the impellor at the heatingcstage or vibrating against the coils.although there is not much movement in the warped plastic, I'm thinking if I can get a couple of mm gap by leveraging off the coils then that might just be enough.

If it is vibration only, I'm guessing I might be able to bend the soft coil fins away from the plastic, although feels wrong.

I'll do some further testing tomorrow. Like I say since removing the front panel and refitting on the backplate, the problem hasn't been as frequent.

Just a quick update - well I wedged a 1mm plastic spacer between the coils and the rear plastic back of the unit and the noise has gone away. I guess it is a case of put the front panel back on and forget about it.

Onto the next problem...I seem to be getting a fairly loud vibrating noise from the outdoor unit, particularily when the fan speed is changing. There is nothing obviously loose on the casing (although the sound is definatley coming from it) and wondered whether it might be just the affects of vibration on the unit. It is on a cantilever style plastic polyamide bracket. Unfortunately I bought into the marketing bumf which said that as it was plastic it would have natural vibration dampening. Hence, I didn't put any extra vibration protection on before it was installed.

Do you think I might benefit from fitting something retrospectively between the unit/bracket and what would perhaps be the best product for this purpose (I see there are a range of rubber type products out there).

Thanks for your help as ever, appreciate it.

DamianAttachment 11759

the fan motor is mounted to the frame with rubber mounts- if the condenser has been bounced when it was fitted then it could be twisted- check the gap between the fan blade and the outer rim, also try putting a bit of pressure on the front plastic fan guard, then other parts- :eek: