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p38A Air Con


beng
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Well my Diesel P38a has never had working A/C since I got it. The book symbol only seems to come on when I turn the A/C on - its fine when the A/C off button is pressed. Is there a relay in the fusebox that I can frig out to see if the compressor clutch has failed? If so does it have to be professionally un-gassed before i can do anything. Unlike you V8 boys my compressor is way down at the bottom of the rad. Anyone else come across similar problems?

Ben

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Hmmm, not sure, but can anyone help with this: the a/c works fine, engages etc but if i stop after driving for a while and than try and restart, the a/c doesn't work. If i then pop the bonnet and push the clutch on the compressor it starts spinning and everything is fine!

What do you think is wrong?

Ric

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If so does it have to be professionally un-gassed before i can do anything. Unlike you V8 boys my compressor is way down at the bottom of the rad. Anyone else come across similar problems?

I'd guess your truck's old enough to have CFC coolant in the air con? In which case the answer, at least from a legal point of view, is yes, you have to have it done professionally. Not sure about the modern coolants. That's certainly the case with the air con in the classic, with the added bonus that the new eco-friendly coolant attacks the original seals so you have to replace all the seals in the system before it can be regassed. Makes it a bit pricey :(

Have you got a circuit diagram for your truck Ben? Even if not you can probably just disconnect the loom from the plug on the air con clutch and jumper it straight to the battery to test it.

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Hmmm, not sure, but can anyone help with this: the a/c works fine, engages etc but if i stop after driving for a while and than try and restart, the a/c doesn't work. If i then pop the bonnet and push the clutch on the compressor it starts spinning and everything is fine!

What do you think is wrong?

Ric

If prodding the clutch works it's not an electrical or coolant fault, pretty much got to be the clutch itself.

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If prodding the clutch works it's not an electrical or coolant fault, pretty much got to be the clutch itself.

Ric,

Have heard rumour of wiring harness not giving quite enough voltage to the clutch - I believe it is an electromagnetic thingie.... Try putting 12v straight from the battery to the clutch +ve

Then you will know if it is power or worn clutch. If worn clutch then I think David Sparkes wrote a fairly comprehensive article on it :-)

Ben

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I'd guess your truck's old enough to have CFC coolant in the air con? In which case the answer, at least from a legal point of view, is yes, you have to have it done professionally. Not sure about the modern coolants. That's certainly the case with the air con in the classic, with the added bonus that the new eco-friendly coolant attacks the original seals so you have to replace all the seals in the system before it can be regassed. Makes it a bit pricey :(

Have you got a circuit diagram for your truck Ben? Even if not you can probably just disconnect the loom from the plug on the air con clutch and jumper it straight to the battery to test it.

Got the diagram.... considering I spend half my life designing electical circuit schematics it is a poor show I can't work the thing out. Think the design engineer had had a few when he drew it.... will e-mail you the pic see if you can make more of it than I. Cheers Geoff

(PS. CRTT is this w/end - we don't get to play :-( )

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Got the diagram.... considering I spend half my life designing electical circuit schematics it is a poor show I can't work the thing out. Think the design engineer had had a few when he drew it.... will e-mail you the pic see if you can make more of it than I. Cheers Geoff

(PS. CRTT is this w/end - we don't get to play :-( )

That's LR wiring diagrams all over...we've never worked out why my air con doesn't work either (and that's with an avionics tech trying to figure it out for me...). Think I should have the wiring diagrams for your truck, so I'll take a look when I get a chance.

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Two separate queries in one thread; plenty of scope for confusion,

Ric,

You don't say but I'll guess your car has one of the V8s in, as the lazy clutch fault affects those more than the Diesels

There are two cures for a lazy AC clutch, one is low voltage, the other is wear.

I don't recall what permanent cure LR created for the low voltage, but the Technical Bulletin solution involved fitting an additional relay, number 9 in the fuse box I think.

To counteract the wear in the clutch, shims can be removed to put the two halves of the clutch closer together.

I don't run a petrol, but ISTR the repair can be done in situ, without draining the AC system.

If you are going to DIY you need the manuals. Green Oval.com is the source. Those CDs have the Technical Bulletins on them so you can at least read up about the problem first hand.

If you want experience from others, look on Rangerovers.net, both on the main site and the 4.0/ 4.6 Forum. Too many Yanks for my taste (and patience) but there are Europeans there as well so you can get some sensible answers.

Beng,

Never worked since you got it - so anything and everything could be wrong.

Pound to a penny it's out of refrigerant, so that's the first thing to fix. Lack of refrigerant means lack of pressure, so the clutch operate circuit is broken by the pressure switch. The mosty common cause a refrigerant leakage is a corroded condensers, the radiator type thing in front of the engine radiator. To see this at all closely you MUST take off both the grill AND the panel above the fans. Don't tiddle about with a torch peering through small spaces. Look for obvious corrosion, and perhaps a green staining if it was filled with a leak indicator. You can change these yourself, condensers are available on ebay, but if you haven't done one before, and you are a bit of a novice, perhaps you should leave it to an AC man the first time. Bear in mind you can expect to spend 200 to 250 GBP to have it fixed. Maybe more if someone stings you for a new Drier.

There are other causes of failure, like pressure switches and blend motors, but you need to check there is refrigerant in the system first. BTW, it's R134, there is a sticker above one of the headlights to confirm this, so you don't have to worry about additional problems caused by changing refrigerant.

As with Ric, browse Rangerovers.net for details of other things that go wrong. I doubt there will be much on the main site about diesel engined models, but some of the Europeans in the Forum run them.

Cheers

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Ric,

You don't say but I'll guess your car has one of the V8s in, as the lazy clutch fault affects those more than the Diesels

Ric's truck is indeed a V8.

If you are going to DIY you need the manuals. Green Oval.com is the source. Those CDs have the Technical Bulletins on them so you can at least read up about the problem first hand.

I'll have a look on the CDs I've got and see if I can find those tech bulletins, Ric - think I've got the right ones for your truck.

Gut feeling says that it's a worn clutch, and the higher temperature when you restart it is resulting in it going just a little further out of adjustment so it slips. Guess there could be extra loads on the wiring when starting from warm, but I can't think of any... :unsure:

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