Check this out.

[GeoffBooth]

Hi Les,
Hooked up a gauge to the large pipe, small connecter ( the cold one) I believe this is the low side.
To begin with it read 35psi
Started engine, blowers on low, the pump was cycling normally, blowers on full. Rose to 48psi. Only one condenser fan kicked in. Pump cycled rarely. Blowers on low, dropped slowly to 39psi.
But the pump was cycling less frequently than at the beginning.
Ran it for 20 minutes blowers mostly on high then shut engine off. The fan clutch was reasonably cool to the touch and turned reasonably easily. None of the previous problems happened through this time. Thing is though The gauge slowly rose to 90psi and stayed there.
Started engine , blowers on low drops slowly to 45psi. Blowers on high 55psi. Ran it 5 minutes didn’t cycle. Shut down engine. Slowly rises to 90psi and after 45 minutes it now read 100psi.
None of this sounds right

[GeoffBooth]

Ok then, may be this is norman. Just the system Equalizing
pressure when shut off and the ambient temp etc.

Could be something to do with the condenser fans may be. Only saw one running on high. Nothing on low speed but they used to work before. Now they don't run at all. High or low.

Could this cause the problem?

[Les Parker]

Have you tested the A/C fan temp switch?
Also I suggest checking the refridgerant and compressor oil levels.
Are there any leaks from the system?
Has this been converted to the later R131a ?

[greghaugen]

With all the bizarre electrical symptoms make sure the relays in the engine-compartment fuse box are good. You could try replacing the A/C relays just for good measure, even though you may hear them clicking. Also, the circuit board itself may have been cooked and causing weird problems. Several traces had overheated on mine and I think had contributed to spotty A/C compressor performance.The 38A fuse box circuit boards commonly fail. Refer to rangerovers.net for more info.

Cheers,
Greg