Problem with new air conditioning

[timeforachangepart2]

We had air-conditioning units fitted about 2 months ago.

One in the loft and two in bedrooms on the first floor.
They keep turning themselves off and the red light flashes five times.
We can turn them off and turn them back on again and then the same thing will happen.

The company who fitted them are telling me it might be because I set them all to 18.
They sent an engineer last week who refilled the tank outside and when he tested it everything was fine. Yesterday though the problem recurred and since then, I can’t get them to stay on at all even individually and set it 21.

Does anyone have any experience/knowledge please?
thanks in advance

Bump

Obviously don't know what systems you have but I can have all 3 of our systems on the lowest temp, 16, and it doesn't cause the issues you describe. Have you tried troubleshooting with the manufacturer directly rather than the fitter?

Thanks for the reply. Engineer is here now and says he found a tiny leak so he's fixed the pipe work, re filling and then we'll try again.

But I agree, if we have problems again I shall go straight to Mitsubishi.

The handsets with our units show 18 as the lowest.

See what happens after today's visit but I would contact the manufacturer if the fault persists ☺️