LG Multi-F Max Mini-Split not shutting off. Help

[MJockey]

I have a LG LMU600HV Multi-F Max, 5 Ton multi zone mini-split in installed in my garage. I have 3 indoor units, two downstairs(LSN180HSV4, LMN248HVT) and one upstairs (LMN248HVT). Everything was working fine until the outside temps started dropping to near or below freezing. I have the units set to heat mode and temps set to 60 degrees F. In the past when I have left them on and the outside temp was in the 40s they would warm the shop to 60-62 then shut off. The last couple of mornings it has been below freezing and in the morning both downstairs units were still running even thought the room temp (on the remote) was 63 degrees. The upstairs unit was off and the room was 60 degrees. Upstairs the ceiling is 8' but downstairs it is a 12' ceiling. The unit are mounted at 7'.

Has anyone had this problem or know of a solution?

 

[Katodog]

Is there an auxiliary heat feature? Our RTUs at work have aux heat, when the temp outside hits a certain low and the main can't keep up, the aux kicks in to give a "helping hand". I just worked on a unit yesterday that was giving problems. The aux heat was on and the room the unit was feeding was cold. Went up on the roof and found the blower motor belt way loose. The aux heat isn't enough to heat the room, and if the blower isn't putting out air the aux heat just thinks it's too cold for the unit to keep up.

You might have something like this, and if so the main isn't working so the auxiliary heat is working, which isn't enough to heat the room(s).


Sorry but I can't explain it any better without writing a small book Hopefully you understand, and if you have a feature like that you can figure out what's up.

 

[MJockey]

There is no Aux heat feature.

Maybe I not explaining it right. The The mini-split has no trouble heating the space and there is plenty of 100+ degree air coming out of the units, but as they approach the set temp they start throttling back and then stay in the low speed/power setting but never shut off. Both the IDUs and ODU keep running in reduced power mode. If I could force the unit to run in full power mode until the set temp is reached then I think it would work better. I can't find any setting in the installation documents that would allow me to set it to be a little more aggressive in reaching its set temp.

Also I think it has this issue because of the large amount of space above the downstairs units, because the upstairs unit, with only 6" between the top of the unit and the ceiling, works fine.

 

[MJockey]

Just in case someone in the future has the same problem, there is a way to change the amount of temperature rise needed before turning off. It is not in any manual. I had to call LG support and they were able to talk me thought the steps. That seems to have fixed the problem.