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You may have to they are in demand. Or you could get this one. Hevac Control Unit (heat & A/C) Models with Heated Seats - Genuine Land Rover at www.rimmerbros.co.uk
air con relay
- Thread starter boycie
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This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
You may have to they are in demand. Or you could get this one. Hevac Control Unit (heat & A/C) Models with Heated Seats - Genuine Land Rover at www.rimmerbros.co.uk
Datatek
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You have confused me, I have always understood that the later cars have the relay which is why no gas does not cause a fault, early ones had no relay and the HEVAC switched direct and monitored clutch current. I'd have to go look to be certain, but I'm sure mine has the relay and it's a late 2000MY.JFC101890 was fitted VIN number WA381431 to XA411504. JFC102550 is the latest version. Mine was made 1998 registered 1999 it has the latest JFC102550 fitted but no relay 3. Aircon works fine from it. But i do have a spare one just in case.
Boycie, the easy answer for you is to fit a dummy load across the relay coil, a 21 watt bulb would probably suffice.
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Relay came in at MY 1999. Instead of switching compressor clutch through pressure switch direct from Hevac unit pin 7 of C244. Both plugs C244 early and CO792 99 on are identical with same pin outs and colour codes. Pin 7 99 on pulls relay 3 and powers compressor clutch from fuse 27 via pressure switch. So as far as i can see it should not matter what unit you use, pin 7 on C244 or CO792 Hevac either powers clutch or pulls relay. There maybe an additional relay in the early Hevac don't know.
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Datatek
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But the early HEVAC requires a minimum current draw from the compressor clutch or it drops out, the relay does not draw enough current for the HEVAC to register clutch operation, so a dummy load is needed
Late cars have the relay, early cars do not. An early HEVAC can be used in a late car if a dummy load is used across the relay, late HEVAC cannot be used in an early car as it does not have the power to operate the compressor clutch direct, unless a relay is added.
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You won't get a clutch open circuit fault on later versions because the pressure switch is not directly in circuit with the Hevac as it is with earlier ones. Don't forget there were some software changes at some stage. Reference ambient air sensor and such.
Datatek
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That's effectively what I said. I don't think you will find other software changes will affect the compressor operation.
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But the early HEVAC requires a minimum current draw from the compressor clutch or it drops out, the relay does not draw enough current for the HEVAC to register clutch operation, so a dummy load is needed
Late cars have the relay, early cars do not. An early HEVAC can be used in a late car if a dummy load is used across the relay, late HEVAC cannot be used in an early car as it does not have the power to operate the compressor clutch direct, unless a relay is added.
Mine has JFC102550 fitted and worked fine when i had gas in without relay 3. Mind you i have never checked if it has been modified. There is a mod for fitting early Hevacs on later models on some site will try and find it. Here you go OP will find this interesting. Range Rover P38 Maintenance repair improvements and tips learned by experience by ownership.
Datatek
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That link gives the same information I gave but with a bit more detail
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That link gives the same information I gave but with a bit more detail
A photo says a thousand words.
boycie
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I have seen that Datatec and thought that may be the answer but was unsure which resister to get or were to get it .If you or Wammers have any suggestions as to a possible type and source please please feel free to let me know .
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boycie
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Finger's crossed ,hopefully he will be back on here and point me in the right direction.
Datatek
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As I posted earlier, a 21watt lamp connected across the relay coil would be a cheap way of providing the necessary load, if it doesn't work with that, try 2 lamps. I have no idea what the minimum load required is for the HEVAC, but if the compressor clutch coil takes 3 amps and the HEVAC needs to see 3 amps, you would need a very large expensive resistor to do the job.
Maybe best to link out the relay
V/I =R 13.5 volts/3amps = 4.5 ohms, I squared times R = W so 9 X 4.5 = 40.5 watts so 50 watts for safety.
boycie
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I have removed the relay to a safe place and bridged the across the switch contact terminal connections and every thing works fine .
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boycie
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Got one in the car , I do want to replace the existing one with the correct unit I have tried but keep getting the old model ,one is going back Monday for a refund.I now know the correct part number so I can ask for the correct item all I kept getting before was it will fit from 1995 -2002 then I had to fit it only to find the bloody thing did not work.
boycie
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I have only had this car for about six weeks I had a couple of Disco 1's over the last few years, and I have to say this car can be a bit of a pain as far as the electronics go BUT it's quite nice to work on its mechanics. My angle grinder ,club hammer and chisel ,hacksaw and nut splitter every day tools for a Disco 1 are gathering dust in the garage .I was given a set of shock absorbers with this car and all I needed to change them was a few spanners and sockets ,try that on a Disco !.
brianp38dse
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Working on then isnt bad finding out what is wrong thats the real pain in the backside,
Atleast they dont rust like the discos as you said
Atleast they dont rust like the discos as you said
boycie
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Yes that's about right ,and I don't miss getting covered in rust and crap every time I get under it and try to undo a nut or bolt like I did with the Disco.
