defrost mode...

[back2space]

Ok so whilst my LG system seems to be working ok, when it has been switched on for 2 hours, perhaps only one unit demanding heat so unit is not running at full capacity it seems to go into defrost after 2 hours, there is no ice build up on outdoor unit and defrost only lasts 3 minutes before it starts blowing warm again.

It never used to defrost after 2 hours unless it was really cold out and its 9c out today. It would do a defrost after 5 hours of low load even if no ice on outdoor coil which seemed normal.

Inside temps are being maintained ok but just wondering if theres a pattern to the defrost cycle.

I know it works on coil temps etc, but the point before defrost kicks in the air off temps are fine.

Thanks.

[Brian_UK]

I've forgotten which model condensing unit you have, can you please refresh us?

Do the LG manuals have any specifics on the defrost regime? I'm just wondering whether things change depending on the number of units connected (Shrugs shoulders as he writes).

[back2space]

I've forgotten which model condensing unit you have, can you please refresh us?

Do the LG manuals have any specifics on the defrost regime? I'm just wondering whether things change depending on the number of units connected (Shrugs shoulders as he writes).

FM25AH UE1 is the outdoor unit.

Nothing that I am aware of the system goes into oil restoration mode every 5 hours of the system being turned on in heat mode, even if compressor hasnt run up 5 hours.

Perhaps with it being cooler outside compressor needed to get itself lined up perhaps after two hours, havent noticed it since.

[cadillackid]

minis and multis usually work off of the middle coil pipe temperatrue sensor on the outdoor unit in conjunction with the outside temperature sensor.. LG has a decently advanced defrosting algorithm.. however if one of these sensors is roque and not reading correctly it can skew the defrost..

usually these are thermistors and often the manuals have the resistance vs temperature chart in them so that you can test tomake sure they are good...

if for say the outside temp sensor on the outdoor unit was bad and reading below freezing it will trigger a timed defrost regardless of the actual coil temp... if one of the coil sensors is bad it could tell the computer that the coil temp is below freezing when in actuality its not...

another thing that will skew it is if the refrigerant is low it will tend to freeze across the expansion device.. however you usually will notice loss of air quality indoors if this is the case....

-Christopher

[back2space]

Last night outdoor temp of 3C indoor temp of 23C and maintaining at this.

ONly one indoor in operation so outdoor unit over sized technically at this point... however we seemed to be having really poor air off temps and therefore room temp was dropping slowly to 22C but inverter was ramped up as it would when raising room temp by 1C.

The air off temp was about 30C. I checked the outdoor coil but it was not iced up and water was happily trickling off the coil underneath and good rate of airflow out the front so I wondered why heating performance had dropped so much.

Today when it is now 1C outside the air off temps are normal?

It seemed to struggle last night from about 2am but is working ok again today?

I put the unit into cooling and the outdoor fan was running faster than it perhaps would at 3C ambient? Normally just ticks over when its cold ouot.

Any idea what could be happening?