My W250 wont charge the battery or the a/c clutch will not engage. I used a power washer to clean the engine before removing the injection pump for rebuilding, replaced the rebuilt pump and noticed that it wasn't charging and the a/c clutch won't engage, I have check everything and I suspect the powertran control module. It's a 93 model, is that likely? If so where is the best place to buy one?

 

Was it charging before you power washed the engine? If it was then you can presume you pumped water into some place it is not supposed to be. Many places to start but I would suggest that you start by unplugging the plugs on the alternator circuit, checking them for corrosion, dirt etc and then plugging them back in. Start the engine and see if that works. If not then do the same for some of the major plugs on the engine. You can also try spraying WD-40 on the various plugs and try and work it in.