C4 Picasso AC problem

[razvanlb]

Hello, I own an C4 Picasso from 2011 with climatronic and i have the following problem:

1. AC works only from time to time, usually when i start the car from aprox 10 secs and then later when radiator fan kicks in.
2. Interior blower the same, zones don't work, blower speed doesn't work.

On diagbox i have no errors, ac compressor is new, condenser is new, freon level checked. Citroen dealership has no idea what can cause this, they suggested to start replacing parts(which i have to buy), first interior blower control module, then climatronic module. I don't want to change all the parts until i find the faulty one. Any ideas what can cause this?

[xantia_v6]

If the engine ECU detects a problem with the cooling system, such as a problem with the fans, or a problem with the thermostat, it will stop the A/C compressor from engaging.

Do you know if the engine ECU codes were read?

[razvanlb]

There are no codes on BSI, ECU or AC ECU.