Anyone knows what's the problem?, With AC on, it is still under 1K RPM
 

As everyone know .... in mostly every car, when you turn the AC on... the RPM gets up ..
In my RX7 91 NA ... it's usually 800 RPM, and when i turn the AC on ... it does not go up .. so when im driving, the engine sometimes turn off in the 2nd gear!

What do you think the problem is ?!
I dont know what's the name of the thing that makes the RPM hikes up when the AC is on, but im sure i need to replace it!

any help is appreciated..! :)

I'm not 100% sure with 2nd gen cars, but on FB's it's the BAC... Bypass Air Control valve.
They can fail, just like any other mechanical piece, or could be somthing as simple as a dead relay/solenoid, or even an unplugged wire.