Air Con Problem

[silversurfer]

I have a 1997 4.6 up until a couple of days ago air con was working fine. Went out yesterday and discovered it has given up the ghost! If I disconnect the plug on the back of the compressor and run a direct feed from the battery, it works fine and blows ice cold. Tried swapping the relays around with ones that I know work but still no joy. Any ideas??? Thanks in advance.

[steve_d]

Don't know about yours but many systems have both over-pressure and under-pressure switches (often in the same switch body = 4 wires). This lives in the top of the dryer. If your system is low on pressure it may have shut down to protect itself.

Try it later in the day when, hopefully, it is warmer and see if it works then. If it does then the system needs re-pressurising.

Steve

PS You may find that letting the engine get up to working temp will warm things under the bonnet sufficiently to get the pressure up a little.

[silversurfer]

Thanks for that. When you say low on pressure do you mean re gassing? Also you say the switch is located on top of the dryer whereabouts is that located? First RR.

[steve_d]

Yes, possibly needs a re-gas.

The dryer should be mounted somewhere around the offside inner wing. There will be two rubber pipes connected to it.

It's most likely black and about the size of a small thermos flask.

http://t3.gstatic.com/images?q=tbn:Uo3rlPZ8gnLMFM:http://gemstreetrods.com/air_conditioning_-_receiver_dryer.jpg

Steve

[David Sparkes]

Time to look locally for Air Con specialist that doesn't charge an arm and a leg. I found one who did home visits to be cheapest, and most thorough.

Obviously there could be a variety of issues causing the compressor not to switch on.

The issue which 'happens to any air con system' could be low pressure caused by gas leaking away, probably from a failed condenser (the slim 'radiator' in front of the coolant radiator). If, repeat IF, the problem is a failed condenser, these can be bought and replaced on a DIY basis, as there is no gas to collect (to prevent it fouling the atmosphere). You will most likely be re-using the O-rings that seal the pipes, so treat them gently.

Price condensers on eBay to get a ball-park figure, although I bought locally.

If you have never seen it done on a 38A, this is an adventurous repair if you are also in-experienced with the 38A.

The issues 'specific to the V8 38A' have to do with:

A/ Low voltage to the clutch. There is a Land Rover electrical modification to overcome this. It's detailed in the Technical Bulletins, which in turn are included on the RAVE CD.

B/ Wear in the electromagnetic clutch causes the air gap to become too large. Sometimes a tap on the compressor, while the engine is running, 'proves' this, as the jolt causes the clutch to engage. The clutch can be stripped and shims removed to eliminate this fault.

This cure is not part of the Land Rover manuals, instead look on www.RangeRovers.net.

So, three things to do.

1/ Download a RAVE CD from the Green Oval site. (Google).

2/ Find, bookmark, and spend time reading, the 38A pages on www.RangeRovers.net.

3/ Find a local A/C specialist.

1 and 2 help you with any and every fault you have on the 38A, and are absolutely essential.

3 is specific to this fault, but even if not required this time, "time spent in reconnaissance is seldom wasted". You will need this resource sometime.

HTH