S13 a/c

[santiaguero]

need some help with the a/c, when i bought the car someone had the a/c conected to a switch on the bottom of the dash, the a/c works but drops my rpms when in idle, i connected it to the original plug on the compressor but i wont turn on by the dash control, my question is, is there a relay that controls that or do i have something messed up in the wiring?? is not the controls cus i changed it, what could it be? i want to hook it up to the original contols on the dash so that when i turn it on it doesnt drop my rpms.

 

[Fingerz]

theres an ac relay under the airfilter box ,i think it should be brown and a fuse by the driver side dooor.