Hey folks, I have an ‘82 300D running an aftermarket Sanden AC compressor. It works quite well, but it has an extremely strange interaction with the tachometer. When the AC is on and the engine is between ~3000 and 3500 RPM, the tach jumps to 5000-6000 rpm. I re-capped and re-soldered the tach amp, and aside from this oddity it works perfectly. Any ideas what might be going on?