trouble with SLK 230 AC
 

Over the past year I've been going through a SLK230 for a friend. Rebulit the engine, checked out all the other systems, got the top dialed in. Last thing is the AC. I pulled a vacuum on it for about an hour and then closed it up and let it sit over night came back the next day and it was still holding the vacuum. So I felt like the system was leak free. When I went to hook up my gauges I could find the low side port but not the high side. I started to charge it up and I could tell the Freon was going in but the compressor would never kick on. I'm not sure it's actually turned on in the inside because unlike most cars there isn't an "AC" button. I rolled both control knobs all the way to blue, and turned the fan on full. I put a little heat to the can of Freon and got the low side pressure up to 65 PSI. But the compressor still wouldn't kick on. It has sat that way for 3 days with no loss of pressure. All the fuses are good.

One thing you want to mak sure is that the “EC” button is not on (lit). That turns off AC.