Yesterday, I posted that I had an CC Problem with my 02 Disco.

I had replaced a faulty compressor and drier, evacuated the system and recharged.

After doing all that the a/c system would not keep running unless the relay was jumped then it worked fine: cold air at the vents, 30-40 low pressure and 190 high side. The only problem was that the system would not run unless the relay was jumped. I left the cotter pin in the relay and drove it around like that for an hour yesterday. I forgot to take the jumper out last night. When I went to start it today the vehicle was dead as a door nail. I had to use a 40 amp charge for a half hour before the engine start was would even work.

After I got it started, I put the relay back in thinking: better to be hot than walk. For some amazing reason the a/c blew super cold like 38F at the vents and works better than ever.

I don't know what I did other than running the battery down to nothing which is the same as disconnecting it but for some reason it made the system work again.

I got lot's of good advice from people on site, Thank God for that, most of the advice leaned toward testing the pressure switch, which was my idea too, however I jumped that like is frequently done to get it suck refrigerant when the pressure is too low but it didn't make a difference.

The ONLY THING that helped was basically disconnecting the battery.

These systems are more complex than your old fashioned a/c systems there are all sorts of inputs from sunlight sensors, exterior air temp sensors, interior air temp sensors etc. So I have concluded that repairing them is more of an art than a science .

We knew that if the compressor worked when jumped it couldn't be the compressor or any of the hard components e.g evaporator, expansion tube etc. We knew that if jumping the shut-off switch didn't make a difference it had to be upstream of the relay.

To my best guess something in ECU or climate control head had to be reset.