Hi, My car air-conditioning was not working so I had an air-conditioning expert look at it. He said there was a bit of gas in it and so did a leak test with Nitrogen. It held pressure and so he said there was no leak. The compressor clutch was not engaging so he said I needed a new compressor which would be about £400 pounds to replace, I told him I didn't want to spend this kind of money.

I bought a second hand compressor cheap and connected a car battery to the two terminal lead and it drew a lot of current and the lead got hot very quickly. I measured the resistance and it was a dead short. I measured the resistance on my fitted compressor and it measured 3.5ohms, better I thought, I then connected a car battery to the lead, it drew a lot of current wires got hot and I heard a fizzing noise. I then measured the resistance again, this time it measured a dead short.

I thought the clutch was operated by an electromagnet, maybe this should have been pulsed with a short duration of voltage and maybe the engine should have been running to hold the clutch in.

Does anybody on this forum know the technical internal workings of a car A/C compressor to shed some light on this?