I have recently picked up an LG heat pump dryer that had been discarded. It is only 3 years old.
Model DVH5-08W.

I have only had a basic look at it so far, it appears to be more or less working, but...

1. it doesn't appear to be drying very well?? So far I have only tried a couple of tiny loads, basically a large hand towel to test it on the quick 30 / 1kg cycle. The towel at finish was warm and steamy but not dry.

2. There is a fan behind a louvre at the back, it doesn't appear to turn at all. I think it is the evaporator fan, but it might only be used for the condenser clean cycle???

This model doesn't have an access panel to look at the condenser, like other heat pump dryers I've seen. But it does claim to automatically clean its own condenser.

I have marked one blade of the fan with a dot, after doing the quick 30 cycle the fan blade had not rotated, so I suspect this little fan may be faulty. It looks like a little generic fan, probably easily replaced. After running a while, the fan louvre gets cold so I think it is an evaporator fan, if faulty that would explain poor performance.

Does anyone who knows these LG heat pump dryers have any advice?

I'm very busy at present, so I may not be able to follow up for a bit, I apologize in advance. (getting ready for a trip...)

Thanks.

Thanks Henrik, very helpful.

What you say about small loads vs large loads agrees with what I saw today, I dried a small load of maybe 5 to 10 items, socks and t shirts.  I did a regular cottons cycle, it worked fine enough and everything was dry. (cupboard dry setting.) The fan on the back still didn't move... I assume that's a fault? It took a long time to heat up, several minutes, but it did heat up OK eventually. If that rear fan isn't working, it would not work as effectively, is that right?

This dryer is inverter-driven compressor.

I just watched the second video, that is fascinating.

I will do a few more loads, some larger ones, and maybe it is OK? Or maybe it needs cleaning out. It certainly seems to have lint dust after the filters, as far as I can see without dismantling.

I had misunderstood how the heat pump dryer worked, I thought it was like a split-system air conditioner and took ambient room air, gathered heat from it ( through an evaporator) and transferred the heat to the dryer's internal airflow. The second video explained that all the added heat is from waste heat in the compressor, which it why it takes up to 15 minutes to get up to full heat. Explains why the rear fan may only work intermittently or not at all on small loads/short cycles - I thought it was moving room air through an evaporator. So the rear fan is just to cool the compressor if it gets too hot?

The fan did NOT operate at the end of the cottons cycle, so it doesn't seem to be part of a cool-down phase. There didn't really seem to be a cool-down, or it wasn't very effective - the clothes finished still quite hot.

I did a reasonable size load yesterday, it worked perfectly and... the rear fan came on after a while. So all is good.

The only thing I can fault is a slight squeak / squeal sound inside when running with a load (didn't hear it before with a tiny load), it sounds like maybe a slightly slipping drum belt?

I will open it up when I get back and give it a clean out and check over.

I can't believe it was thrown away, it's an AUD$1500 dryer here, barely 3 years old.