Problem (but no fault code) with an LG UU-48-W

We got a call this morning to an LG unit which the customer said wasn't heating.

There are 2 x UU-24 (I think the letters are right, it's definitely 24) indoors off one UU-48-W outdoor.

The "house" button says the room temperature is 18* but even if we set the stat to 30* the outdoor unit won't cut in.

The hard-wired display doesn't show "pre-heat" or "outdoor".

We tried it on cooling and it cut in and ran for a short while.

Two of the compressors feel stone cold and one is slightly warm (this could be due to the couple of minutes it ran on cooling).

There is no fault code showing up anywhere.


Any ideas?

Check thermistors for proper R/t relationship.

Will check it.