E30 S54 Swap AC signal input to DME

[gpeterson]

^I sure hope you get a response! I'd love to utilize my s54 compressor vs swapping in my old S52 variant.

That is what I did on my E36. Should be nice since it is a variable-displacement compressor that will cycle off & on less.

I actually took it a step further by replacing the A/C pressure switch with an E46 pressure sensor, adding the E46 radiator outlet temp sensor, and wiring an E46 PWM aux fan controller to the E36 fan. My custom CAN board reads the pressure & E36 snowflake button signal to request A/C from the DME and let it control the aux fan, same as it works in the E46.

The CAN board I built also has an output to turn on the check engine light. It is also possible to provide output signals for cruise/EML/oil warm/oil level/shift lights (digital) as well as oil temp (analog).

I had to make custom A/C hoses by TIG welding some E36 & E46 parts together and have them crimped by a hydraulic shop:










I cut the top from an E36 pressure switch, welded the top shut, and drilled/tapped it for the E46 pressure sensor:




The E46 threaded temp sender in the head has the same electrical characteristics as the non-threaded one in the lower radiator hose, so I used one of those hose sender adapters re-drilled and tapped with the correct threads:




The E46 PWM fan controller works great with the E36 (or likely any other) aux fan:

[R3Z3N]

^I sure hope you get a response! I'd love to utilize my s54 compressor vs swapping in my old S52 variant.

[328ijunkie]

ZM3 is CAN as well.

I yelled at my buddy, ill see if return my call :P

[nando]

how does it work on the Z3M? it could be just a byte config to use a hard input instead of the CAN bus. I'd start with the Z3M S54 ETM..

[8920vt]

I cant get ahold of this guy. No calls, text, or emails responded to. Lost cause.

Id honestly have paid this dude for the electrical schematic and built my own but I cant get any response. Oh well

[Staszek]

Subscribing I need one as well!

[R3Z3N]

Looking for a good solution as well.

[8920vt]

Well this seems to be a lost cause. No responses

[slampig]

Is there a solution to this problem for people running OBD 1 swaps?

[8920vt]

PM sent. thanks dave

[Andrew325is]

I get asked this all the time. If we can direct people to a good solution that would be awesome.

[328ijunkie]

I can contact him for you. I helped him make it :P. PM me your #.

[8920vt]

Thats what i am curious about if anyone has had success creating a control board to mimic the canbus signal.

This guy i was talking to claimed to have done it, but before i could get any more from him, he fell off the face of the earth.

[DesertBMW]

it is all CAN BUS network so it is not possible without some control board that mimics that.

[8920vt]

So I love my s54 e30. Its been tearing up the road for 2 plus years now. When I initially did the swap, i did the standard e36 m50 ac compressor install and all the r134a conversion. The ac is great cruising down the highway to a car show.

Here is the dilemma, i have studied the wiring charts and am racking my brain trying to figure out a way to get AC signal input into the DME so the engine knows when the AC is activated. I hate the idle bog and hesitation of running AC around town stop light to stop light.

I ran across a guy on another forum that claimed to be making a control board that i presume would just take 12 volt signal from the factory e30 switch and convert the input, then send it to the DME via installed wiring and fool the DME into thinking the AC was on, on full load. I was interested in what this guy was trying to do, but he's impossible to get ahold of and he never replies.

So my questions is, has anyone figured out a magical way to get AC on signaling into the s54 DME in an e30 swap car?

Thank you
Ian