I’d appreciate if you guys could help me diagnose this one. When driving my wife’s 92 940 (148k) at almost any speed with the a/c on, it feels like I’m driving into a surging 50 mph headwind. Now it seems to be only with the a/c on.

One thing to note, the a/c is not blowing very cool—and the compressor (part# DKS 15BH - original unit) is cycling off an on way too much—it also rattles/buzzes quite a bit when on. Basically, I’ve dealt with this for about five years, and am surprised that the compressor has lasted this long. All I’ve had to do to keep the system blowing cool is have the original r12 system recharged every couple years due to a slow leak.

But this time, not only do I have the same compressor buzzing and lack of cooling, but the ‘at speed’ hesitation/surge/drag. Last night, after driving the car for the first time (after my wife told me of the problem), I idled it up to about 2500 with the compressor off—no surging. Turned the compressor on and the tach would dive and rise 500-750 rpms or so with the continually cycling compressor.

Is the compressor finally on it’s way out? I know it’s low on refrigerant, but this surging/dragging on the engine is a new experience. Can a faulty compressor actually hurt performance? Gas mileage seems to be down too.
And if the compressor is out, then it’s time to completely redo the a/c system. I checked my favorite parts supplier—FCP Groton—and they don’t sell a/c components. Where do you guys suggest I go to purchase the parts? And what else will I need besides 1) compressor; 2) accumulator; 3) variable oriface tube; 4) refrigerant....??? Would this be the time to convert to R134A?

I know that’s a tall order, but I really would appreciate any help. Best regards.!