What is this vacuum solenoid for?

[MaddieCycle]

'86 KC 4x4 California model.  This solenoid is mounted to the firewall driver's side, noticed the long hose coming off that heads toward the carb is disconnected, can't figure out where it is supposed to go or what this thing is.  Fiche has been unhelpful. Thanks!

[Stoffregen Motorsports]

That's the history erase solenoid. Thank God it's disconnected.

[datzenmike]

Does it have cruise control??

[MaddieCycle]

No cruise control, to my knowledge.  A few unused wiring connectors behind the dash, but no evidence of previously removed cruise control.

[Charlie69]

All my 85/86 720 2wd trucks have that vacuum switch.  It is on the firewall above the above the brake booster.

[MaddieCycle]

1 hour ago, Charlie69 said:

All my 85/86 720 2wd trucks have that vacuum switch.  It is on the firewall above the above the brake booster.

Do you know what it does and what it connects to? I have a hose coming off of it that I don't know where it goes.

[Charlie69]

F.I.C.D. Solenoid

 

 

 

[MaddieCycle]

Thanks Charlie, that is awesome.  Looks like it is an idle compensator for the A/C.  Since my idle hovers around 1000 anyway I've never had trouble idling with the A/C on.  Sounds like it is time to plug that vacuum line and move on.  👍

[Charlie69]

I run the Weber DGEVs and these solenoids are of no use to me so I remove them when I clean up my engine bay.