Hello everyone,
I'm new to this forum.

I have a Daikin Ducted Heat Pump: Indoor unit FBQ71B8V3B Outdoor unit RZQ71B9V3B from 2006.
The indoor unit is installed in the antic between the roof (not insulated) and the ceiling (insulated) therefore hot in summer and cold in winter but the HP duct boxes are surounded with rockwool.

During last summer in southern France, the cooling was really insufficient with air outflow (ceiling outlets) at around 30 celsius while the outside temp was over 35 or 40 celsius.
However, during winter (now), heating works well.
For the avoidance of doubt, the Air filter is clean (there is none in the indoor unit but one at the inflow inlet in the corridor.

Question 1: I suspect that the refrigerant liquid (R410A) should be refilled as it has never been refilled for 14 years. Although heating work well currently I would like not to wait if the efficiency is poor and hence it would cost me more electricity for the same heating. Did one of you face a similar situation ?

Question 2: when I look at the indoor unit, on the left of the PCB cover panel, there is a one inch hole with a quarter turn locking and I have not found on various service manuals what is it for. Could it be used for maintenance like for cleaning something ?

Thanks ahead for your replies.
Apicats