violent idle?

[i2ice4m3]

I just got another 90 240sx 5spd and the idle would become extremely rough from time to time. I give it some gas and then returns to only being a little rough. Also, when I press the A/C button, the green light doesnt turn on, no cold air comes out, but the car idles like crap and doesnt raise to around 1200rpm like it should. any thoughts?

[drjohn]

For the rough idle it could be anything from a bad connection at the coolant temp sensor ,a egr vavle not seating properly,injectors not closing or dripping in the manifold and not spraying evenly or something as simple as a vac.leak. For the a/c check your fuses first and then try pushing the a/c switch in and holding it to see if the light comes on,this would indicate a bad detent in the switch or you could just have a devective switch.

[i2ice4m3]

thanks a lot, man!