I recently had my A/C replaced in my 87 van. Blows cold and no degraded performance. she runs so smooth When the van is at idle with the AC off you would barely know its on, if not for my headers and exhaust. But you turn the AC on at any setting and the van noticeably vibrates, when your driving it is completely not noticeable but at stop lights and such its pretty annoying. As ive stated im still new to this whole fixin/diagnosing car thing, but im thinking something aint right, anyone got any ideas or am I just expecting to much from an 87.

Thanks
Dave

 

There should be a solenoid that kicks the engine's idle speed up a bit when the A/C compressor turns itself on. Sounds like that system is not working properly. I don't know enought about 87 vintage systems but it sounds to me that's where your problem is.

Normal idle speed should be around 750-800 RPM

You might also want to check the condition of the motor mounts, but this is probably a less likely culprit.

 

After trying Rusty's advice and if nothing improves, I'd say there could be too much oil in the new compressor.

 

I had the oil checked in the system and all appeared at appropriate levels. Anyone have any idea about where i could track down this celenoid rusty speaks of or its name. does the EGR valve have anything to do with this - im guessing that thought is out to lunch, but just wondering if they were at all connected cause I have bypassed the EGR when I installed my headers.