Thanks James!

OK, so looking at the new wiring diagram, there's no way for that signal to get into the ECU.

So we will have to wire it in.

Here's my suggestion:

1) Locate the wire between the A/C switch and the thermoswitch (I don't know where this is on the car but I assume the thermoswitch will be in the evaporator, so in the heater box somewhere)

2) On the ECU, cut wire 2L. This is normally a switch which is shorted to ground when we're in 2nd gear. We don't use this.

3) Connect this wire from the thermoswitch to pin 2L on the ECU

4) In the software, change digital input 7 (labelled "Gear 2") to "Elec Load 3"

5) Increase the Extra Idle Effort for Elec Load 3 to compensate for the load of the condenser fans

6) If necessary, reduce the extra idle effort for A/C (because now whenever the A/C is on, the Elec Load 3 will also be on).

Thank you!
Andy

 

Let me give it some thought.

If we're not going to go after this with software I may make the connection under the hood of the car, between the power steering load sensor and the relay that triggers the A/C fans.

Thanks Andy ... I'll post pack ... of course, please let me know if you think that I'm missing something.

 

Hi Everyone,

It's been a couple of weeks now and I'm happy to report that things are much improved with my current setup.

I've wired a relay between ground and the power steering sensor wire. The relay draws power from the A/C fan power feed. I taped into it next to the cooling fan relays in the engine bay. If the A/C fan relay is engaged, the ECU receives a power steering load signal. This seems to work well when the pressure switch for the A/C triggers as the fans are left on.

On the other hand, when the cabin thermo-switch triggers (for the evaporator) the condenser fan's disengage. Overall the ECU is now working as it should as it's receiving the signals that it needs.

I however have a two new issues that perhaps there is a solution to.

1) When I start the car, the compressor turns on too early and stalls the car out. The engine can't seem to make it past 300RPM. The solution is to turn the A/C off, start the car and turn it on. I can live with this but maybe there's a solution.

2) When the compressor engages from an normal idle it sometimes stalls the car. I've compensated by raising the idle to 900RPM and adding extra load compensation to the A.C. It's not the greatest solution. The car dips to 600 RPM when the compressor engages, rises to 1200RPM and then the PID control brings things down to 1000RPM.

I've noticed an Air Conditioner Min RPM setting. Is this the solution?

thanks in advance Andy.

James

 

Hi James, the ideal solution is to run the A/C control through the ECU. Normally we do this but on the RX7 we needed all the outputs for other functions.

If you had another output spare (or when I make an output expander) we'd control the A/C with that one, and then we would make it only come on when the engine was above a certain RPM. Also we make it bring up the idle speed BEFORE engaging the A/C clutch (ie delay the output by almost a second).

At the moment it's a compromise because of the number of outputs but am working on something to change this!

Thanks
Andy

 

OK, you rock ... I've been contemplating what would be involved to create an output expander as suddenly I could have the smog controls working as well as four channel ignition ... and ... and ... and ...

Consider an output expander sold as soon as you create it!

 

I would probably buy an output expander too! Just because I have some ideas for warning systems etc.

 

couple more outputs (one more pwm) on universal ecu and I'll order couple more ecu's