Hi guys, I need help regarding my AC system. I have a sr20det redtop and I bought my car with the AC lines not yet connected. I managed to have a local AC shop connect the lines and make the AC system work. It works fine now. They wired it without any connection to my ecu.

So now here's what's bugging me, running the car while AC is on when I hit the brakes my rpm drops to 500-600 for 1-2 seconds almost close to stalling but never does. In neutral, my rpm is at 850-900(warm engine) and when I turn the AC on it drops to 600 for 1-2 seconds the goes back to 850-900. With the AC off my car runs fine without the rpm drop when I hit the brakes.

What seems to be the problem? Is it the IACV that needs to be cleaned or replaced? I've read that there's supposed to be a wire connection from my AC system to the IACV for idle up is that right? Coz mine doesn't have any. Or is there anything else I should check? Thanks in advance!