A/C, 2speed engine cooling fans and VEMS

[mr_g]

I was looking for this but I couldn't found it...

Newer cars with air conditioning compressor has 2 speed fans (low speed when A/C on, and for up to some temperature point, when high speed fans is powered up). Also A/C has MAP sensor for monitoring pressure inside the A/C system...

Also, when A/C is turned on, idle rpm must rise for about 200rpm... And it must turn off A/C on higher engine loads and when rpm passes like 4000rpm so it wouldn't destroy A/C compressor...

Has VEMS ability to control this?

[rob@vems.co.uk]

There are probably a couple of ways of doing this, here's my guesses:
Wire a relay so that when AC is on the first fan is on, then use the Water pump controller to trigger the second speed over a set temperature.

When idle drops, our idle control algorithm will handle the RPM drop and attempt to return the RPM to the idle target (this take a LOT of setting up, but is getting easier with the newer firmware releases).
Using a Misc Ouput trigger you can turn off the A/C over a specific RPM, &/or throttle position.
I didnt know that it was turned off to save the pump, as I understood it the reason for switching off the compressor was so that if you wanted full power from the engine (over 90% of the throttle) the compressor would be switched off to save parasitic losses.

Rob

[mr_g]

Well, the power also... But the main reason is saving compressor... It could destroy something if the pressure in the A/C system rises to much on high rpms...

So, you think that this could be inserted in VEMS? It's not a problem to me to make another piggyback with AVR to controll fans speeds and A/C (as I got one now on C51 because motronic is moronic), but the point is to have ECU that would replace standard ECU, that controlls almost anything on newer cars (well if the daewoo lanos 2001 make is reference    )...

Motronic is not the best reference... It's pretty old...  It doesn't controll fan LOL, but it does have A/C in switch, that rise idle rpm as you turn on the A/C... But it doesn't have rpm switch...   

Well, I could help development team to extend this...  When I get to that point... Of course...