Brian,

I have the same car, and the KILMA relay is indeed located behind the Battery. Its behind the black plastic cover at the back of the battery. There are several other relays there as well.

You are right, the Mercedes manual does say that the AC compressor will not restart (after it has shut down because it sensed an RPM variance), until the engine is turned off and on again, BUT, it will restart on its own if the shutdown was caused by faulty wiring to the speed sensor. This can occur if the speed sensor wires are intermittently shorting, opening or grounding. In that case, the AC compressor will come back on as soon as the intermittent wiring fault fixes itself. Basically what I am saying is that the system seems to be capable of distinguishing between an RPM variance and a wiring malfunction. In the case of an RPM variance the compressor will not restart until you shut down the engine and restart it. In the case of a wiring fault the compressor will restart as soon as the wiring fault is removed.

I know this for a fact, as I had intermittent defective wiring between the AC speed sensor and the KILMA switch. These two particular wires carry a digital signal, and one of the two speed sensor wires was intermittently grounding, causing the digital signal to be attenuated. (The infamous wiring harness problem) the compressor would then go off and come on intermittently. This, without shutting down the engine. I fixed the problem by running two new wires.

There are several other possibilities. One being defective wiring to the auxiliary fan. This will cause the AC compressor to intermittently shut off as well.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]