If you have no air movement restrictions and the fan clutch is working then the only thing I can think of would be the a/c system itself (i.e. the compressor). It may be placing an extra workload on the engine if there's something wrong.

Eric

 

Because when the a/c is on it dumps extra heat infront of the radiator, that is what the a/c condenser does.
The a/c condenser is a radiator for the a/c, the a/c works by removing heat from the cabin and expelling it to the outside.
The best place to put the condenser is where it gets the best air flow, in front of the radiator.
The electric fans are there only to move air when sitting in traffic and to provide aux cooling in a overheat situation.
The clutch fan is what cools the engine.
No working clutch fan and the engine will overheat when there is extra load placed on the cooling system.
No working electric fans and the a/c will not be cold while idling.

 

My 2000 Disco2 165K, is overheating. It will idle for hours at normal Temp. If you drive and don’t push it, temp. Is ok but accelerate or climb a hill Temp. rises let idle and the Temp. comes back to normal. I have read all I can fine on the form and this is what I have done so far. new O2’s,MAF, Plugs, Wires, bleed air ,look for vacuum leeks and compression test (1,3 2 and 4 90 cold, 5,7 6and8 78 cold).No water in oil and I have not found any one with pressure tester with screw on cap. Eletric fan are working Eng. seem to working. Spin it but hand it will only turn about a half turn. HEPL!!