Greetings, I have a 90 535i and had some A/C work done a while back. System was working great for a couple of months but recently compressor would not come on when A/C selected. This was intermittent as next time A/C was selected it came on just fine and cooled fine. Well now Compressor wont come on at all. Are there some things I can check before I take it in and have it tested? Fuses all ok. One thing I did notice was while checking the relays the relay in the A/C spot,according to Bentley number 5, was missing. I took another relay and put it in and tried it again, still nothing. Can someone check their 90 and see if there is a relay there? thanks..