Split system no sirculation ?

[JAGPURR]

Hi all,
New here so please bear with me.
I have a Ecoair split system about 15month old, model ECO1211S
It seems to work ok in cooling mode but in heat mode after 30min running the gas line from condenser is too hot to touch but no heat from indoor unit. Gas line at indoor unit is only luke warm. If left running outside unit starts to squeal so I have to shut it down. Was told it’s likely to be refrigerant loss but when a retired engineer checked he said the pressures seem normal.
No damage anywhere to lines so what would stop the circulation ?
Someone else said its rubbish so scrap it, just naffed that it is out of guarantee.
One or two pointers as to what to look for would be much appreciated.
Thanks in anticipation.

[monkey spanners]

Dirty filters, not so likely if pipes got cool by indoor unit.
Short of refrigerant. Only way to be sure is to remove it with a special machine and weigh it to see if it has the manufacturers charge in plus and additions due to pipe length.
Compressor worn.
Reversing valve not making full travel in heating mode.

Favourite would be refrigerant shortage, especially if it was a diy install.

[install monkey]

indoor coil sensor- in heating mode it should speed up the indoor fan
normal operation in heating mode would be indoor fan runs at a low speed- compressor starts after a 3 min delay- after about 2 mins the indoor coil will be at 30degrees, then the indoor fan will speed up, typical for coil sensor to cook itself

[JAGPURR]

Thanks for the responses guys.
Checked filters all ok, not sure if it's possible to check valve travel without removal.
Fan does run at low speed initially but pipes at evaporator never reach 30 degrees. putting fan on higher speed manually has no effect. The gas line from the condenser is very hot for about 6 to 10 feet then cools off to nothing as if it's a circulation problem, if a low charge would cause this it's looking likely monkey spanners is right. I do remember that the initial installation used a 10mtr pipe set and it said that this was the max without additional charge so assume only a small drop would cause problems ? does this seem logical?
Thanks again.