allenz71

Hi Everyone. Im having problems with my AC on my 91 mercedes 300se. It stopped cooling late this summer. I checked the freon(R-134) and it said it was a little low. I added some, and then used the vehicle a couple weeks. Cooling stopped again. I checked it, and found that the pressure was then too high. I pulled some freon out to an adequate level indicated by guage. At that point my compressor clutch would kick it, but I wasnt getting any cooling. So I bought a new compressor off E bay. It was a Unicla brand, and has a module to take the place of the speed sensor, and some other sensor on the original compressor. After installation I vacuumed system and added freon. Since then I cant get the compressor clutch to stay pulled in. I have checked the low pressure switch mounted on the drier, and it stays closed, indicating a good charge. Even when I send 12v right to the clutch lead(energizing clutch) the pressure switch stays closed. I cant find a high pressure switch on the car , so I pulled som freon out, and put just enough in to make low pressure switch close with the clutch engaged. I feel like the charge is OK. The guy on Ebay sent me another module to try, and that still didnt work. I was told that after turning on the AC with car running, I should receive a voltage (12V) on the clutch lead for 3-4 secs. I only receive it for 1 second. The clutch engages and releases. Is the caused by the climate control? Can anyone offer me more info on this problem? Thanks for reading.