Hello, I’m fighting with my Fiat for the Ac imput on black and Classic (actually i have a Classic but i will soon switch to a black).
My car has an a/c controller that is sending the request to the original ecu passing trough the a/c pression switch. Is a three stage switch.
I have the possibility to take the pin that I marked with number 40 and connect it to analog in, but I will have there +12v and I think this is not ok. Can you help me? The car originally has a Bosch motronic.
Here some scheme
VG is the wire from the ac controller that sends +12v.
N is the ground and the other two are going to the ecu.
this is typical trinary switch all depends how is connected in a car normally on early cars one of the pair (1st and 3 stage) is connected to the AC button if this is a case now depend what is sending switch when button is on if sending ground you need pullup resistor and connect it to analogue input if sending 12v you can directly connect it to the analogue input . than use this analogue as activation switch . make sure min AC pressure is set 0 and evaporator temp is calibrated properly … if there is separately input for ac activation you need to use it on another input and combine them both in virtual output and use this virtual as ac activation.
Stage 2 set of terminals are used for additional ac fan activation not sure how is this done on that car often is just connected to chassis and is working sometimes is using ecu to activate ac fan
