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Discussion Starter #1
Cut a long story short Have had my range rover p38 4.6 1996 gems for several years, air con never worked.
had it pressure tested, condenser had whole in it.
Replaced condenser and air dryer.
Had car pressure checked and professionally filled at garage(used them before on other vehicles) took around 30 mins and i could see it being done
Air con still not working (didn't expect it would !!)
Anyway left on, by the time i got home, Opened bonnet compressor was trying to spin.
took clutch off front of compressor, completely rusted, cleaned up and was kicking in fine.
However was running for about 30secs then stops for 10 secs , then starts again
checked for power at compressor with multimeter and the power cycles on and off with the wires disconnected, so not the the clutch or compressor ?
The test book light has always come on, but it never had gas then
It still lights sometimes, but i think the blend motor for the distribution flap, plays up, as sometimes cannot get air out of face vents
How ever when i leave say on windscreen the testbook light does not come on
I know there are lots of sensors ,sun,interior , interior fan, trinary switches etc
My question is if set to auto ,should the compressor run all the time,
if set to LO with auto off would the compressor run all the time even say like now the outside temp is say 12 degrees
On my non climate control vectra if i put the air con on the compressor runs all the time, i can even say have the heater on and use the air to keep the windscreen clear
Is this not possible on the range rover with climate control
By the way its nothing to do with say over cooling or frosting up etc, as the compressor will cut out and do the cycle on and off even from first start up
It does seem to stay on more if i put in manual mode and the fan motor on full speed??
its not a pressure problem with gas as icy cold and no leaks when working
must be a sensor ?? I believe the heavac recalibrates itself every time the ignition switched on and off, so doesn't need any resetting by a computer etc ?
Any ideas, or how it should actually work, or is it just too cold outside lol
exterior temp sensor showing correct temp
thanks
 

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1995-2002 Range Rover P38A
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Is the book symbol lit on the HEVAC contol? If so, you need to read the codes. The P38 HEVAC system is somewhat complex, it has two PWM operated blower motors (one per side) and at least five different actuators. Unless you know what's wrong you can spend a fortune on parts and labor and never actually fix it.

If you don't have access to diagnostic equipment, RSW solutions "EASUnlock" v4 is capable of doing everything you need to fix HEVAC. It's a lot of diagnostic equipment for $187.95 + shipping. I installed it on an old Windows XP laptop I had lying around collecting dust.

The PAG oil used for lubricating Air Conditioner compressors is hygroscopic (it sucks humidity out of the air). If the system was open to the elements for years, there is likely corrosion damage inside the AC compressor. You could try getting a used AC compressor form breakers (should be short money) and new o-rings for the hoses. Make sure you get a fresh one, or the one that was stored properly after removal, otherwise it won't be any better than the one you already have. You have to use AC-specific green o-rings, generic black ones won't work. I work on AC in my cars myself, so I invested in a vaccum pump and manifold with hoses. In the long run it's cheaper than paying every time I need to open the system up. On a 20 year old car AC it may take a few tries before you find everything that is wrong with it. In the US we can buy fluorescent dye compatible with AC system and put it in while filling the system. If there are leaks, you will find them easily this way. Not sure if it can be a DIY job in your neck of the woods. Some jurisdictions regulate access to refrigerant.
 

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Compressor will never run all the time, it balances temperature and pressure to keep within the limits. It won't do it in your Vectra either although some compressors are intended to run all the time just not compress all the time so although it appears to be running it isn't doing anything some of the time. Later Vauxhall, VW/Audi and Ford use these and it is very common for the compressor to wear out, especially if the car has been run with no refrigerant.

If you set to LO, the compressor will run for a while then cycle on and off (regularity will depend on ambient temperature), the thin pipe will get hot and the thick one will get cold (cold enough for condensation to form on the outside of the pipe) and you'll get cold air from the vents. On a perfectly working system you can get it down to around 3 degrees C but on an older system anything better than 12 degrees is acceptable. Put it on LO, fans on full and stick a thermometer in the vents to see what you have. The system is a climate control system. You set the temperature you want and it will give you a mix of hot, cold and ambient air to maintain that temperature. As the AC also dehumidifies, the compressor will also kick in when you set it on defrost so it blows dried air over the screen.

Was it done properly or was it done using one of the idiot machines where you poke the buttons and leave it to do it? Usually, if done with the idiot machine, it will have had oil and dye put in it (whether it will be the correct amount is anyone's guess) with the refrigerant.

Yes, refrigerant can only be supplied to a qualified person in UK, Europe, most of the rest of the world and, as the US is also a signatory to both the Kyoto and Montreal protocols, it should be the same there. The two protocols make it a criminal offence (Federal in the US) for any supplier to supply to anyone that cannot show the relevant qualification and/or Fgas registration (of which I have both.....).
 

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1995-2002 Range Rover P38A
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I am sure that you are correct about US being signatory to all kinds of treaties, but I can just go to Home Depot or a local auto parts store and buy as many cans of R134 as I need in the US. I can even have large bottles of welding gases shipped to my door, which in fact I did. No one ever asked me for a license. Venting R134 into the atmosphere is illegal and carries stiff penalties in the US. Nobody does it that I know of, it would be a monumentally stupid thing to do.

I grew up in Europe, they regulate things quite a bit more than US, which is why I asked the OP. They do regulate some stuff in the US, for example I had to get a license to carry a concealed handgun in MA. In many states you don't even need a license for that.
 

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Discussion Starter #5
Compressor will never run all the time, it balances temperature and pressure to keep within the limits. It won't do it in your Vectra either although some compressors are intended to run all the time just not compress all the time so although it appears to be running it isn't doing anything some of the time. Later Vauxhall, VW/Audi and Ford use these and it is very common for the compressor to wear out, especially if the car has been run with no refrigerant.

If you set to LO, the compressor will run for a while then cycle on and off (regularity will depend on ambient temperature), the thin pipe will get hot and the thick one will get cold (cold enough for condensation to form on the outside of the pipe) and you'll get cold air from the vents. On a perfectly working system you can get it down to around 3 degrees C but on an older system anything better than 12 degrees is acceptable. Put it on LO, fans on full and stick a thermometer in the vents to see what you have. The system is a climate control system. You set the temperature you want and it will give you a mix of hot, cold and ambient air to maintain that temperature. As the AC also dehumidifies, the compressor will also kick in when you set it on defrost so it blows dried air over the screen.

Was it done properly or was it done using one of the idiot machines where you poke the buttons and leave it to do it? Usually, if done with the idiot machine, it will have had oil and dye put in it (whether it will be the correct amount is anyone's guess) with the refrigerant.

Yes, refrigerant can only be supplied to a qualified person in UK, Europe, most of the rest of the world and, as the US is also a signatory to both the Kyoto and Montreal protocols, it should be the same there. The two protocols make it a criminal offence (Federal in the US) for any supplier to supply to anyone that cannot show the relevant qualification and/or Fgas registration (of which I have both.....).
Thanks for the reply and the information, so by the sound of it when the test book light is not on, it's probably doing what it should, I'll check with a thermometer, one pipe is cold one hot, yes definitely done correctly, I watched the machine the whole time and it did the count down etc and correct gas and oil measurements was added from plaque under the bonnet, they did my Vectra a few years back after that got a hole in condenser and that's still icy cold
Thank again for the imformation and how it should work
Is the book symbol lit on the HEVAC contol? If so, you need to read the codes. The P38 HEVAC system is somewhat complex, it has two PWM operated blower motors (one per side) and at least five different actuators. Unless you know what's wrong you can spend a fortune on parts and labor and never actually fix it.

If you don't have access to diagnostic equipment, RSW solutions "EASUnlock" v4 is capable of doing everything you need to fix HEVAC. It's a lot of diagnostic equipment for $187.95 + shipping. I installed it on an old Windows XP laptop I had lying around collecting dust.

The PAG oil used for lubricating Air Conditioner compressors is hygroscopic (it sucks humidity out of the air). If the system was open to the elements for years, there is likely corrosion damage inside the AC compressor. You could try getting a used AC compressor form breakers (should be short money) and new o-rings for the hoses. Make sure you get a fresh one, or the one that was stored properly after removal, otherwise it won't be any better than the one you already have. You have to use AC-specific green o-rings, generic black ones won't work. I work on AC in my cars myself, so I invested in a vaccum pump and manifold with hoses. In the long run it's cheaper than paying every time I need to open the system up. On a 20 year old car AC it may take a few tries before you find everything that is wrong with it. In the US we can buy fluorescent dye compatible with AC system and put it in while filling the system. If there are leaks, you will find them easily this way. Not sure if it can be a DIY job in your neck of the woods. Some jurisdictions regulate access to refrigerant.
Thank you for the reply, like I said testbook light comes on sometimes, but narrowed down to distribution flap, blend motor sticking, as when on windscreen or feet in manual mode, does not light.
There was still a bit of green oil which came out of the old condenser, so how much air got in the system over the years is unknown.
I must invest in the eas v4. I do have the older one which does just the suspension.
All the orings on condenser, dryer, switches etc was replaced with correct size new green orings, which I replaced myself
The machine the garage used did a removal of old gas etc first, then a pressure test, this part took at least 20mins and said pass, before it added oil and gas
All hoses and pipes are in excellent condition, so I pretty certain it's either an electrical fault or it's doing what it should
Thank again Brian
 

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If I remember right, aren't you in Wisbech or somewhere local to me (Stilton, near Peterborough)? I don't mind putting my Nanocom on it for you to identify exactly what is bringing the book on so you can sort it.
 

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1995-2002 Range Rover P38A
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If you can't get to Richard, it's probably the distribution motor. This one, out of the three seems to have the hardest load on it; I can hear mine groaning away when I think I replaced it a few years ago (with a second hand one). It will occasionally throw the book up. If you cycle it from highest to lowest range it seems to free it up.

Once the system has sensed an issue with that motor it will not attempt to move it again until next time you start up. If it throws the book then will not respond to any input then it's almost certainly that motor.
 

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The motors usually fail when the flaps stick. You need to remove the dashboard to get to the HVAC unit and repair the sticking flaps. I was told that after two decades the body of the HVAC unit becomes distorted and the flaps start caching on it. They must move freely without catching or sticking. The servos are tiny and weak and the gears in them are plastic. They are not designed to move anything with force.
 

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Cut a long story short Have had my range rover p38 4.6 1996 gems for several years, air con never worked.
had it pressure tested, condenser had whole in it.
Replaced condenser and air dryer.
Had car pressure checked and professionally filled at garage(used them before on other vehicles) took around 30 mins and i could see it being done
Air con still not working (didn't expect it would !!)
Anyway left on, by the time i got home, Opened bonnet compressor was trying to spin.
took clutch off front of compressor, completely rusted, cleaned up and was kicking in fine.
However was running for about 30secs then stops for 10 secs , then starts again
checked for power at compressor with multimeter and the power cycles on and off with the wires disconnected, so not the the clutch or compressor ?
The test book light has always come on, but it never had gas then
It still lights sometimes, but i think the blend motor for the distribution flap, plays up, as sometimes cannot get air out of face vents
How ever when i leave say on windscreen the testbook light does not come on
I know there are lots of sensors ,sun,interior , interior fan, trinary switches etc
My question is if set to auto ,should the compressor run all the time,
if set to LO with auto off would the compressor run all the time even say like now the outside temp is say 12 degrees
On my non climate control vectra if i put the air con on the compressor runs all the time, i can even say have the heater on and use the air to keep the windscreen clear
Is this not possible on the range rover with climate control
By the way its nothing to do with say over cooling or frosting up etc, as the compressor will cut out and do the cycle on and off even from first start up
It does seem to stay on more if i put in manual mode and the fan motor on full speed??
its not a pressure problem with gas as icy cold and no leaks when working
must be a sensor ?? I believe the heavac recalibrates itself every time the ignition switched on and off, so doesn't need any resetting by a computer etc ?
Any ideas, or how it should actually work, or is it just too cold outside lol
exterior temp sensor showing correct temp
thanks
I have exactly the same situation, but my fans dont switch on, the large ac hose get cold and the other one hot, but due to the fans not running the system does not get very cold. i suspect the pressure switch on the dryer is fubar so will need to change that or the trinney switch.
 

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Which fans are you talking about? The condenser fans or the blowers? Dead pressure or trinary switch and it wouldn't work at all.
 

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I don't think they come on in normal operation in cool conditions; it needs to get pretty hot out there for them to kick in.
 

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Discussion Starter #13
condensor fans not switching on, but the ac compressor cycles , pipes get cold and hot as should do.
I think they call them ghost fans, as they never work, I have shorted mine and they work fine, apparently they meant to also kick in if the engine overheats, but when I had a blocked radiator and it would boil up in a few miles, red light on temp gauge, they never kicked in, originally thought it was a cracked block, or slipped liner, but some idiot years before as the heater orings was leaking had put the gunge stuff in, cut rad open and found completely blocked, pics on here somewhere, so they probably only work in really hot conditions, unfortunately now we entering the beginning of winter, but air con is definitely working really handy for keeping windows from misting up, still cycles on and off, looking forward to summer to see if it operates well in hotter weather
 
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