Using the 1227747 and a York compressor plumbed as an air compressor. I know the 7747 is capable of increasing the idle speed when it senses that the compressor clutch is engaged. Is there a maximum RPM that the ECM and increase the idle to?

What I was thinking about doing was setting the value to about 2000 RPM and adding a toggle switch in the A/C signal sense wire. With the switch off, and the compresser engages, it would run at whatever RPM the engine is currently running at. When NOT DRIVING, and I want the engine idle higher to increase volume output of air, I could turn on the toggle switch and whenever the compressor clutch engages, it would automatically up the engine idle to 2000 RPM. When the compressor clutch disengages, it would drop the engine back down to normal idle.

Sound doable?

 

The concept Sounds do-able. The switch would be in the signal wire to the ecm, right? That way, the compressor clutch could operate based on compressor demand while driving, but the ecm wouldn't "see" it. Then, while stopped, you could let the ecm "see" that the compressor clutch was engaged and up the RPM. I don't know how high the IAC will bump up the RPM though.

 

Correct.

Quote:

I don't know how high the IAC will bump up the RPM though.

I guess that's the real question here.

 

This could be a problem if trying to add 1200 rpm to the A/C on during idle. (figuring a base idle of 800)
You may have a hard coded Idle speed limiter, There is in $8D mask. I'm not sure what bin/mask you have.
While it can be changed in the code, doing this will only be in effect when at idle IIRC.
The problem is that you will uncap your idle speed maximum and "may" creep up on you if in a colder climate. You may start the car one day at a 2000 rpm idle.
Like I said, I'm not 100% sure but you should investigate that possibility.

Edit:
You may also have a power steering "cramp" pressure switch input that may perform the function better than the A/C logic.