'96 x300 A/c Heater issues....

[Switch]

Afternoon all.

I'm having some trouble with my x300's air conditioning.

Bought it last year and was told there was a lack of gas in the system, so I didn't think much about it as it was cold and no AC was fine by me.
Fast forward to now and I'd dropped the car off with Garaged.com while I was out of the country rather than leave it in long stay (I'd highly recommend them(shameless plugging)) and they mentioned that because my AC wasn't cold they could get it topped up while I was away, lovely idea I thought.
Anyway, when I got back I was told that the system was infact full and seemed to be able to blow cold-ish on the passenger side but warm on the drivers side.

I spent this morning prodding the system, booted into test mode (Auto and recirc) and got codes 23 ( Refrigerant pressure switch malfunction Harness ) and 24 (Face vent demand potentiometer fault Potentiometer open / short circuit Harness / connector fault Refer to PDU).
Cleared both of these and ran the diagnostic sequence (recirc button). Let it run for a while. and then restarted the whole lot.

Now I'm not getting any error codes (I'll go back and check again after it's been sitting for a while) but I'm now only getting hot air again. And the system seems to have started "hissing" quietly when AC is selected (sounds like gas moving through a narrow pipe rather than escape. But I've never heard that before today.

It would seem to me that there might be a problem with the routing within the system that seems to not switch the airflow through the cooling part of the system rather than the heater...

I'd appreciate any thoughts you might have...

[LMV600]

The hissing described in normally indicative of low gas charge in the system . I would be having this checked by a specialist prior to doing anything else .