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1995-2002 Range Rover P38A
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Discussion Starter #1
Gents,

I've got a 1996, 4.6 HSE, I've got her on the road since last week, and the aircon pump isn't turning when the engine runs.
It looks like the aircon is normally on and you can switch it of if you like.

There where a few relays missing in the fuse box, I put other relays in, and hoped this would fix the problem, but unfortunally, it didn't.

I checked all relays and fuses, all are ok.

I measured the voltage at the connector at the pump, and this was zero, I also connected my battery charger (2 amp) to the wires from the pump, this didn't make the pump turn over...


And now I'm out of ideas what to do.

Anyone who can point me in the right direction?

Thanks. :)
 

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1995-2002 Range Rover P38A
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359 Posts
Discussion Starter #2
I did some further investigation, 2 amps is not enough to get the pump turning over, when I used jumper leads and connected that to the pump it started turning over.

When I stick a wire in where the relays should be the fans start spinning, but when I do that with relay number 18 nothing happens, so it looks like something wrong between the relays and the switch..
 

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1995-2002 Range Rover P38A
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359 Posts
Discussion Starter #3
Gents,

I found writing on this forum regarding the aircon pump not engaging, looks like this happens more often.
I read about the trinairy switch, I can't find the location of this switch.
Is this switch in the front near the radiators?

Thanks
 

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1995-2002 Range Rover P38A
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359 Posts
Discussion Starter #4
I've been asking questions way too soon, again....

Location of those switches are under/behind the L/H side bumper.

When I bridge the connector the pump engages, and turns off when I push the button on the heater panel, also the testbook indicator doesn't come on anymore.

There's no cold air coming out of the vents, so she needs to be regassed, no surprise there because she hasn't been running for about 8 years.

But I still have a question, is there a way to find out if the switches are still in working order? I read that these switches read the pressure in the A/C system, and when the pressure is too high or low it switches off the AC pump.

Thanks
 

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1995-2002 Range Rover P38A
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1,295 Posts
Take a breath and read Workshop Manual- Section 82- Air Conditioning- Description and Operation in RAVE. It tells you what and where the components are and how the system works.
You can bridge or disconnect various elements of the two pressure switches to see how the system is functioning, but you can't test a positive pressure switch is functioning correctly without pressure.
Don't know what they do in Aus, but over here you'd pressurise the system with Nitrogen and a UV dye, which would highlight the leaks and, assuming you can get the system to hold pressure, you can then test the functioning of the pressure switches.
An aircon system that has been dormant for 8 years is likely to leak from a lot of places anyway, as the seals deteriorate and no lube is circulating.
 

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1995-2002 Range Rover P38A
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1,422 Posts
As OB says, without gas it will not run.
DO NOT try to bridge switches and run it aside from quick tests as it will destroy the compressor without r-134 in there to circulate the oil. The system is designed to protect itself from under and over pressure, so do not defeat these systems. I know from recent experience that it is just about a federal crime in Oz now to re gas your own system, so get it to a shop and have them look at it. I like the nitrogen test method. Very "EU" environmentally friendly (and costly?) The gas has most likely escaped from the rotary seal on the compressor, as this requires rotation to maintain a gas tight seal. If not used for a period of time, in your case 8 years, it has dried up, but may not be faulty. talk to an aircon shop......
 

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1995-2002 Range Rover P38A
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Discussion Starter #7
I wasn't going to do that, and this is something I will not do myself.

Thanks
 

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Something to remember that up to 1998 the Compressor was driven directly from the HVAC control panel. 98 and up received a signal from the panel which triggered a relay in the under hood fuse box to power the compressor. A few older P38s were fitted with a retro fit harness and relay, but not very many. Another option for you is to remove a shim from the clutch assembly on the compressor so that when activated it takes less energy to close the clutch.
 

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In the US, Land Rover used to sell (and maybe still does) sell a retrofit kit to update the older version to the newer. My first P38 was a '95 and had issues with AC. I had the retro kit installed and drove that P38 another 4 years without issue.
 
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