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1995-2002 Range Rover P38A
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Discussion Starter #1
It was a refurbished unit.

Any ideas what the problem might be? Is it possible I got a bad one? All the controls, lights, and LCD screen work perfectly, but now the A/C doesn't blow cold and the book icon symbol appears after about 5 minutes of the car running..

Thanks mates.
 

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1995-2002 Range Rover P38A
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1995-2002 Range Rover P38A
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89 Posts
Discussion Starter #3
Yes, I believe it was for my year. All the connectors fit fine. It was just a direct swap.

Yes, exactly. My air worked fine before. Blew cold, I just couldn't read the screen because the pixels were messed up..

Now AC does not blow cold and book icon comes on. Perhaps I just need to reset something? (Hopefully)
 

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1995-2002 Range Rover P38A
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Discussion Starter #4
Yes, it was a refurbished unit I purchased on eBay. I sent them back the old one for a core charge (now I kind of wish I didn't! Haha)
 

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1995-2002 Range Rover P38A
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The issue I was reading was not the connectors it was the wiring , I may be wrong but try checking it out.
 

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1995-2002 Range Rover P38A
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No they aren't. One drives the AC compressor directly the other drives a relay to drive the compressor. Did you make a note of the part number of the old one and compare it with the new one so see if they are the same?
 

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1995-2002 Range Rover P38A
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No I didn't.

I'm afraid I might have installed the wrong one then! Strange how all the plugs are compatible (plug and play), but the actual functions aren't..

Anyone happen to know the correct part # so I can begin my search to fix this? It's a 2002 model year.

I'm so annoyed with the whole thing right now!
 

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You can try using the working display board with the original lower PCB. This way the main electronics are correct for the vehicle. worked for me.
 

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1995-2002 Range Rover P38A
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He can't as he got the new one on an exchange basis so doesn't have the old one any more. I believe, and Marty_nz is the man who will be able to tell you, that there is a wiring loom that can be added to make a different one work although I was under the impression that you needed the loom to use a later controller in an earlier car and not the other way round. Checking RAVE shows that an early HEVAC switches the compressor directly while the later one switches a relay which suggests that if you've been supplied with an early one it should still work (as you will already have the relay). Unless it is clever enough to detect that it isn't supplying enough current to pull in the compressor clutch and is seeing that as a problem. If you do have an early HEVAC, it should be easy enough to put a jumper in place of the relay so it drives directly but I'd be inclined to check the part number on the replacement HEVAC and then, assuming it is an early one, go back to your supplier to get the correct one.
 

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1995-2002 Range Rover P38A
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Discussion Starter #11
Yeah, I will just try to get the correct unit. I just hate having to open everything back up again! My fault for not doing enough research first..
 

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COnsidering you are in SoCal why not check with Scotty for a known working unit?
 

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1995-2002 Range Rover P38A
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Here's a print-screen of a table of all the HEVAC controller part numbers and which supercedes which part number. As far as I know a newer part number can be used in an older vehicle, with the compressor upgrade harness.

To use an older unit (where it drives the compressor directly) in a later vehicle (where it already has a relay in the fusebox) then I would think you would need to put the harness in line BEFORE the fuse box to simulate the load of the compressor that the older units are expecting.

HEVAC Controllers.jpg

Hope this helps you find out what part number you have/need.

Marty
 

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1995-2002 Range Rover P38A
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Discussion Starter #15
Thanks for the info Marty! I pulled the unit back out of the truck today. Part # is AWR1012. I believe that is from an older model (1995?), thus not compatible with my 2002 without some fiddling with...
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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Your 2002 model should have a JFC102550 unit installed as standard,

AWR012 is one of the earliest models that supports heated seats and heated front screen - so whilst all the features are there, it is designed to run the AC compressor directly. The 2002 will have the relay in the fuse box to drive the AC compressor directly from a battery feed (via F27 and RL3). Because the relay coil draws very little power, the HEVAC will not see enough load on it and think that the AC compressor isn't running - and thus probably shut off and throw the book symbol.

The easiest fix is obviously to put in the correct HEVAC unit for your year (maybe see if the company who sent the refurbished unit can swap it?) or failing that, install a power resistor in the feed to the fuse box relay, to then up the current draw from the HEVAC, and thus trick it into thinking that it's driving the AC compressor (basically what the Power Harness upgrade did on the earlier models)

Marty
 

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You need to calibrate it with a testbook or similar. This could explain all your symptoms. The testbook and the temperatures being all wrong can be because the calibration is wrong. I'd start with that before swapping hevacs again. I suspect the old unit would work fine in a new car but I've never tested it.
 

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1995-2002 Range Rover P38A
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Discussion Starter #18
Your 2002 model should have a JFC102550 unit installed as standard,

AWR012 is one of the earliest models that supports heated seats and heated front screen - so whilst all the features are there, it is designed to run the AC compressor directly. The 2002 will have the relay in the fuse box to drive the AC compressor directly from a battery feed (via F27 and RL3). Because the relay coil draws very little power, the HEVAC will not see enough load on it and think that the AC compressor isn't running - and thus probably shut off and throw the book symbol.

The easiest fix is obviously to put in the correct HEVAC unit for your year (maybe see if the company who sent the refurbished unit can swap it?) or failing that, install a power resistor in the feed to the fuse box relay, to then up the current draw from the HEVAC, and thus trick it into thinking that it's driving the AC compressor (basically what the Power Harness upgrade did on the earlier models)

Marty
Hey Marty, got the new unit in! Haven't had a chance to install it yet, but the model # is JFC 102550. Do you have any info on it? That should work yes? Looks like it's from a newer model..

Thanks again everyone!

Darvin
 

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LEGACY VENDOR
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JFC102550 was the latest version of the HEVAC unit and supercedes all the other units, so should be fine :)
 
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