E30 compressor issue
 

Recently i did a so called retrofit on my 88 325is from R12 to R134. Now when i turn ac on the clutch engages and it blows cold alright but then it disengages, some seconds later engages again and off again. What causes the ac clutch to engage and disengage is it dying or sensor related? Thank you

Could be either unfortunately. AC systems cycle the compressor on and off to prevent the evap from freezing. When you did the refit did you first replace all the old black r12 seals with the brown r134a seals? if no, there's part of a problem. Did you leak check the system? the cars are older leaks are inevitable. R134a is not a direct fill replacement either, you only put in about 80% the fill capacity of r12. Retro fitting is a bitch which is why most shops won't do it because it's less expensive to just fix it and fill with r12 even at 25 bucks a pound. I did a refit, replaced the compressor, all the seals, the h-block, the receiver/dryer, and even got stuck replacing both the sensor switches, and still r134a just isn't that great, it does work but I kinda wished I stayed r12.