GenBoard/UnderDevelopment/FirmWare/AirConditioner (2005-08-14 22:28:49)

'''Air Conditioning clutch output ... subpage of

GenBoard/UnderDevelopment/FirmWare'''

Many ECUs control Air Conditioning (AC) clutch output. Currently there is no firware feature for AC in GenBoard/VerThree, but it seems fairly simple.

MembersPage/MarcellGal is not an AC expert, but studied his air-conditioning system (can post scanned schematic, but it's nothing more than described below, with some hardly readible Italian abbreviations).


Air Conditioning clutch output:

Clutch active when signal +12V. appr 450mA (26 Ohm)


Air Conditioning clutch output activation rules


Main fan activation rule

Note that the main fan usually draws 30..40A - almost always a relay is used and a 50A fuse.

The main fan is the 2nd biggest current eater (after the starter motor).


Input signals

AC system pressure signal

Naturally, a single pressure sensor can be used instead of the above range switches (eg. an MPX700A).

Other signals


Misc stuff

These might surprise the unaware, when debugging an AC system:


Some systems are certainly different to some degree.

Automatic AC systems have somewhat more parts, eg.