[Bahmanson]

Hi, i have 2005 330CI Automatic. Next month i'll buy E90 335i Manual as a donor. Im planning to N54 6 speed manual swap to E46. After several month of analyze and search i decided to buy Ant Steering & Electronics n54 e46 swap wiring conversion kit and drift hq engine and trans mount kit. But i have a problem with a/c. I want to keep e46 stock just swap engine and trans from e90. I saw some people swapping hole e9x into car or placing climate control to the glove box for a/c compressor signal. I dont want to do this. I contacted with Ant Steering guya they said with their kit there is no solution a/c work. Some guys say e46 a/c compressor works with 12v on/off signal but e90 a/c compressor works with 0-100% pwm signal and i need to do something to convert 12v on/off signal to 0-100% pwm to a/c work, some people say some n54's come with 12v on/off signal a/c compressor. Do you guys have any information any advice for ?
Thank you all !

[SRLA]

From what I can gather the N54 uses a clutchless variable displacement compressor, the compressor is always turning and the PWM signal sets the position of the swash plate and so the internal displacement. Completely different from your typical compressor (like the e46's) which is fixed displacement and all the 12V signal does is engage an electromagnetic clutch.

I can't find any info on the exact parameters of the PWM signal and how they relate to compressor displacement, you would need to have a running e90 and an oscilloscope to read the PWM signal in real time in different operating conditons (I would expect it to be at maximum displacement when set to max cooling at low engine speeds, and then PWM is reduced as engine revs increase to prevent excessive refrigerant flow). Then you'd need a PWM generator to mimic this signal (not too difficult job, join any electronics DIY forum and they'll help you with the schematics for it).

It would be less hassle to get a different (conventional) compressor that fits, if that's possible, or if not just use the e90's climate control module as you mentioned.

[Bahmanson]

Thank you for your attention and info. It seems i need good electrician to do this job.

[whyzee125]

Two potential options:

1) use the e46 compressor with a custom fabbed bracket to mount it to the n54 and a custom length belt to fit

2) use something like a VintageAir electric compressor designed for retrofits and just bypass the stock n54 compressor altogether