I just purchased a 2005 (Built 4/04) Scion XB. The a/c doesn't blow cold. The light comes on on the dash when pressed. I appear to have power at the plug on the compressor (my multimeter died today, hence appears. Using the old test light) but the clutch doesn't engage. On the car side of the compressor plug there are two wires, one black with a white stripe and one blue with a black stripe. According to my wiring diagram, the blk/wht goes directly to 12v hot via a/c 2 fuse 7.5 amp. The fuse it good. The power is good. The blu/blk wire goes to the engine control module (ECM). I presume the wire going to the ecm is a switched ground wire? On the compressor side of the plug, there are 2 wires. One is black, one is red. I have grounded one side and 12v the opposite, I have done the same reversed, and I have applied 12v to both prongs and the clutch magnet still doesn't engage. Here are my questions....

1. Does the ECM in fact use a ground to switch on the compressor?
2. Are my original test procedure correct, ground one side of the compressor plug and 12v the other prong?
3. Do they sell just a clutch for the compressor, or do I have to replace the complete compressor?
4. Is this a common part to fail on these?

I think you have the wrong forum, this is for the 2nd generation xBs, 2008+
You might be able to get better help in the 1st gen forums!