AC Issues, Bad Condenser, Evaporator, or just a leak?
 

Hi all, long time lurker first time poster. I've got a 2005 e83 which seems to have a stubborn ac issue. The ac will not blow cold until the car has been driven fit while (ten ish minutes) and when it finally does, it only blows really cold out of the drivers side. The passenger side is always warmer. Now I've done a LOT of searching on the forums but I have yet to find a definitive answer as to what I'm looking at.

I've replaced the diverter valve on the drivers front wheel well and that didn't help. I've confirmed that the compressor does switch on as soon as the button is pushed. I had an ac shop check the system for leaks and they said the system holds pressure just fine and was "full" So now I'm a little lost as to where to go next.

My only other symptom is a strange whistling noise that occasionally comes from under the dash after the ac gets cold. It sounds like one of those sealed water bottles that's been slightly cracked open so a tiny bit of air escapes. O hand no idea if that has anything to do with this.

I have experienced those symptoms of one side colder than the other when the system is low in Freon. I added a can of freon with the UV dye and after some weeks traced the leak to the low pressure valve cap, replaced it and has worked perfectly for the last 6 years. The diverter valve on the driver's side is for the heater coil.
My guess is: the expansion valve on the evaporative coil.