No. The compressor is always running, what changes is the displacement of the compression strokes. There is a swash plate inside the compressor that is solenoid controlled, and varies the stroke of each of the 7 pistons.

On ECON, or even when the system is turned off completely, the swash plate goes to its fully retracted position, minimizing piston stroke, however (as mentioned above) that still has a ~5% compression, so the pistons are still moving. They aren't moving much, and compressors come pre-filled with oil, but I personally wouldn't risk the possible damage to the brand new compressor by driving the vehicle. Starting it up to make sure it is installed, and belt is routed correctly will be fine, but extended runtime could easily compromise the new compressor.

 

So I had the AC compressor replaced as two shops recommended and now I still have no AC. The AC compressor doesn't engage unless it is manually given power. What are your thoughts? Is it the AC control unit?

Which would also mean that the AC compressor was not bad to begin with.

 

Anyone know if I can replace pressure sensor switch without all my freon escaping? I heard some vehicles have a schrader valve under them. Is this the same with the LR3?

 

I'm having your exact original problem* with a 2013 D4. Did you find a solution in the end?

* AC works fine for a while, till things get hot, then it suddenly stops working, fan blows regular air. Restart the car a bit later and all is fine, for a while, again.

 

The link below is to a number of files related to the HVAC system of my LR3. I expect the 4 is not much different.
One of the files within is a 21 page pdf with 1786 views so far explaining how the system is supposed to work. You may find it helpful.

Generally I find most of the problems with my 3 are wiring related, not really mechanical.

When you read the 21 page pdf, you will find that the AC compressor (page 10/21) does not have a clutch like most cars have, but instead there is a solenoid valve that controls the flow of refrigerant out of the compressor. The valve is controlled by the ATCM, code for the panel mounted HVAC controls.

I think an AC compressor that does not have a clutch is foreign to most AC fixer types, hence you have to provide the system info and then find out if your fixer of choice has any familiarity with these sort of systems. If it is like the ZF trannys, most LR dealers only know how to replace stuff, not fix the problem - hence you will likely have to understand the system so as to explain it to your fixer of choice.

Our HVAC systems might be on the newer Ford Navigators and the big Lincoln, hence Ford dealers sometimes know how to fix this stuff.

DISCO3.CO.UK Photo Gallery - Heater Air Conditioner System

 

Thank you very much for a considered reply. Yours is sound advice but all a bit daunting(!) I'll try to more precisely establish the sequence that results in the A/C not working (just how hot the car must be, if that is even the problem, when it switches back on, etc) and establish if there are any better than average A/C mechanics in the area.

cheers

 

The reason I mentioned Ford is that they used and I think still use Land Rover as their test mule for production innovations worldwide.
LR is about the only vehicle that has mass world wide distribution in both LH and RH drive country's regardless of climate - jungles, the near arctic, deserts, urban, rural, you name it, LR is everywhere.
Look at the exhaust piping visible at the rear of the current Explorer station wagon line - same split pipe setup we have as a result of independent rear suspension; the difference was our vehicles were produced in the late two thousands.
It is the same with our PCM/PWM alternator control systems - now current on most Fords.
Our no clutch AC units were and are still cutting edge, and you are doing the bleeding.

 

That's really interesting. Bleeding edge indeed. By the way, talking of Right hand drives and various parts of the world, my 2013 LR4 is in South Africa.

 

I am having this problem, intermittent operation, on my 2012 LR4. Took it to a shop and they say the compressor is failing, needs new compressor, condenser, and expansion valve to the tune of $3300. If I had thought it was the compressor, I would have replaced it myself, but given that it works sometimes, although doesn't blow cold enough ever, I'm inclined to think this is a control issue and not a compressor failure. If the compressor was failing, I doubt it would be working at all.

 

to give some closure to my question .. in the end it was just the compressor control valve. The AC has been fine ever since.