Completely wet ceilings

[Groenendij]

Hi!

Whenever it rains a whole day outside, the ac wall units get a big wet circle around them on the ceiling above (see pictures). We have had the AC units for about 4 years, and this is the first time it is happening. It keeps happening to two of our ac units. We can hear the waterdroplets constantly drop to the ground and into the AC wall unit. After turning the AC unit off, the unit feels very very hot to the touch.

The unit is mounted 5 cm from the ceiling. Could this be the cause, must the distance between the air intake and ceiling be more than 5 cm (2 inches)?16158161591616016161

What could be causing this?

After the company serviced the units, mysterious black streaks started appearing on the left and right side of all out AC units. We also do not know where the brown streaks are coming from. When touching it, it feels like crystals have formed in the brown droplets and it also feels a little bit oily.

Manufacturer: Mitsubishi Electric
Model: MSZ-LN18VGW

Hope to solve the mysteries soon!

[Rob White]

.

Hello Groenendij

You say when it rains?

Is the roof leaking?
Have the drains been connected to a drain that is also fed with drain water?

I would look to the rain being the issue rather than the AC it's just coincidence that the water drips near them.

If the ceiling dripped water anywhere else when it rains would you automatically assume the AC was the issue?

If it is not the drains and rainwater it must be condensation?
If the humidity in the room was so high and the ceiling was cold then moisture would condense out of the air onto the wall.

I have seen this in a cold-room but not an Air Conditioned space.

I have seen it when a customer used an AC system to keep a room full of cut flowers fresh in a florist and had it set so cold it caused the moisture in the air to condense on the ceilings and walls.

Regards
Rob

.

[Tayters]

Unit in cooling? Perhaps there's so much moisture in the air the AC so somehow making the nearby walls cold enough for them to sweat?
Sounds a bit daft but that's all I can offer other than trying a higher fan speed - if you are in cooling that is?

Otherwise if the unit is hot then you are in heating mode?? Is the outdoor icing up/defrosting and that water is finding it's way in?

Cheers,
Andy.

[Groenendij]

Thanks for the answers!

By combining your answers, I figured out what is going on.

We had the valves of the AC facing the ceiling. The air was cold, so the moisture condensed on the nearby ceiling and parts of the nearby wall.