Quote:
|
Originally Posted by Dave
E67 can and does control compressor - in factory installations. Issue is it gets AC request from HVAC module over CAN bus. And I don't see anyone that is going to solve that puzzle anytime soon.
Best solution is to allow Vintage Air (or whatever) unit control compressor, and ECM control fans. Again, you can set fan DC based on AC pressure (which is why you need to install sensor in AC line and wire to ECM).
|
Thanks again for all the insight and answers. I love this stuff!
If the V/A (or ISIS) controller manages the compressor, then there must be a sensor to know when to turn off the compressor when liquid side pressure gets too high. So we're back to a trinary switch (maybe just a binary switch?) to do that -- negating one of the key advantages of having the ECM manage the fan. I suppose it's still better for the ECM to manage the fan (does it soft-start the fan to reduce inrush?), but this hybrid system will have two pressure sensors that aren't integrated.
I'm going to talk to ISIS about their V/A controller and whether or not it can be modified to support the CAN-bus protocol to be able to talk to the ECM. I'm sure Jay's question will be: what is the CAN-bus sequence to tell the ECM to enable the A/C clutch?
Edit: I realize that just the CAN-bus electrical connection isn't enough. GM has a proprietary protocol that would have to be reverse-engineered to get this to work. I also asked ISIS about their ability to read CTS and A/C sensor data and manage the fans. I'll report back.