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1998 Lamborghini Diablo SV
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Discussion Starter #1
After a week of freezing temps, it's now the beginning of 'spring' in south Texas. Humid as hell and 'only' about 80 degrees out. I took a 30-45 minute drive and at no point was the A/C doing a good job. Climate control was set to LO and middle fan speed (tried the highest setting but it just blew more warm air on me).

A/C was apparently not working well when Roy got the car and had it serviced at Veloce

293077


This was 6 months ago. So.....it should be working.
Car came with the owners manual from a first gen Diablo, so I'm not sure what the climate controls are supposed to look like, but the button that controls the fan speed (bottom right) has what looks like a window defroster icon. And despite which button/buttons I pushed, air did not come out of the side dash vents.

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I assume I'm not missing a separate button to turn on the A/C compressor?
If I don't get this sorted, this car will be undriveable for about 6 months out of the year.
Gotta love vintage automobiles!
 

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maybe you do not have a fan speed button and that truly is the defroster button. if you select the left top and left bottom and hit minus placing it to the desired temp down to something really low do you get cold air.
 

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1998 Lamborghini Diablo SV
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Discussion Starter #3
maybe you do not have a fan speed button and that truly is the defroster button. if you select the left top and left bottom and hit minus placing it to the desired temp down to something really low do you get cold air.
I kept the temp down to 'LO' the entire time. The bottom left button (red) definitely controls the fan speed (it illuminates the 3 green lights). The top right (white) blows air at max speed through the center vents which I assume is the front defroster. Having them both pressed at the same time just blows air at max speed through the vents. I didn't keep them both depressed long enough to know if the air actually gets cooler, but not sure why it would??
 

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After a week of freezing temps, it's now the beginning of 'spring' in south Texas. Humid as hell and 'only' about 80 degrees out. I took a 30-45 minute drive and at no point was the A/C doing a good job. Climate control was set to LO and middle fan speed (tried the highest setting but it just blew more warm air on me).

A/C was apparently not working well when Roy got the car and had it serviced at Veloce

View attachment 293077

This was 6 months ago. So.....it should be working.
Car came with the owners manual from a first gen Diablo, so I'm not sure what the climate controls are supposed to look like, but the button that controls the fan speed (bottom right) has what looks like a window defroster icon. And despite which button/buttons I pushed, air did not come out of the side dash vents.

View attachment 293078

I assume I'm not missing a separate button to turn on the A/C compressor?
If I don't get this sorted, this car will be undriveable for about 6 months out of the year.
Gotta love vintage automobiles!
Besides checking for leaks and putting freon into the system, they should have extracted all the old freon prior to charging the system with new freon.

I doubt they screwed that up.

the other area to look at is the pressure sensor that triggers the AC compressor to start/stop. There’s also an AC fuse and relay can go bad that controls the signals from the dash to the AC system. NOTE: these suggestions are based on MY history with a normal car, NOT a lambo.

oh, the compressor itself could be faulty. I wonder if the prior maintenance inspected It. You can YouTube various methods of troubleshooting AC systems.They’re all similar.

just brainstorming

good luck!
 

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97.0 VT Roadster / 08 Gallardo Spyder
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I’m not sure exactly how to service AC compressors as I’ve never done that before but Josh checked for pressure leaks and that was only six months ago. Unless it was a very very small non-detectable leak that accumulated over six months, which is a possibility, I might lean more towards the compressor or wiring/fuse. if I recall correctly from when I replaced my belts this last summer I believe the AC compressor has a small wire coming out of it that you might want to check for corrosion.

That said, here is what that unit in the dash looks like in my 97. I don’t have a second defrost switch though mine is a roadster and it’s possible you have in a coupe a rear window defrost? That switch box is very solid state but the buttons are fairly easy to switch out, as someone who owned it prior to you has done. not sure why they would have done so as I would suspect almost every part of the system before that switchbox. The bottom right switch for fan speed is a four-position switch: 1-2-3-off.
 

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97.0 VT Roadster / 08 Gallardo Spyder
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Bonehead, I couldn’t help but notice three things on your photo as well. First, I love the carbon fiber! Second, I note that your error light is not blinking but your auto light for the ride adjustment is on, both good. Finally, around that ride adjustment switch is a rectangular panel that from the looks is sticky and losing its original finish. Mine was too. It is about a $30 part and was very easily changed out. The back of it is three very small I believe 3mm nuts and popping up your carbon fiber tunnel and replacing that panel is not a hard task for aesthetic look.
 

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1998 Lamborghini Diablo SV
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Discussion Starter #7
I’m not sure exactly how to service AC compressors as I’ve never done that before but Josh checked for pressure leaks and that was only six months ago. Unless it was a very very small non-detectable leak that accumulated over six months, which is a possibility, I might lean more towards the compressor or wiring/fuse. if I recall correctly from when I replaced my belts this last summer I believe the AC compressor has a small wire coming out of it that you might want to check for corrosion.

That said, here is what that unit in the dash looks like in my 97. I don’t have a second defrost switch though mine is a roadster and it’s possible you have in a coupe a rear window defrost? That switch box is very solid state but the buttons are fairly easy to switch out, as someone who owned it prior to you has done. not sure why they would have done so as I would suspect almost every part of the system before that switchbox. The bottom right switch for fan speed is a four-position switch: 1-2-3-off.
I'll give the compressor a look.
Rear window doesn't have a heating element. And it communicates with the engine compartment. With all that heat, there wouldn't be any need for a defroster back there.
Still confuses me as to why someone switched out the fan button to that. It's the same size as the other buttons, but I'm not aware of any other Diablos having a red window defroster icon??

Bonehead, I couldn’t help but notice three things on your photo as well. First, I love the carbon fiber! Second, I note that your error light is not blinking but your auto light for the ride adjustment is on, both good. Finally, around that ride adjustment switch is a rectangular panel that from the looks is sticky and losing its original finish. Mine was too. It is about a $30 part and was very easily changed out. The back of it is three very small I believe 3mm nuts and popping up your carbon fiber tunnel and replacing that panel is not a hard task for aesthetic look.
Thanks. The CF is a nice touch. It's definitely showing it's age. A bit scuffed and yellowing, especially on the door sills and the engine compartment.
As far as that rectangular bezel, it's pretty scuffed, but I don't think it's sticky. Where can I source that piece?
 

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97.0 VT Roadster / 08 Gallardo Spyder
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Bonehead, I think I got mine from Bull stuff or AMH parts. They are both great, and you can try eurospares.com as well. You could also try your local Lamborghini dealer for a hearty laugh.
 

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That red bottom right button should not be there. That's the fan speed button.

For reference, I am in Australia, so HOT summers. Working Diablo Air Con has no trouble coping with the heat here.
 

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I kept the temp down to 'LO' the entire time. The bottom left button (red) definitely controls the fan speed (it illuminates the 3 green lights). The top right (white) blows air at max speed through the center vents which I assume is the front defroster. Having them both pressed at the same time just blows air at max speed through the vents. I didn't keep them both depressed long enough to know if the air actually gets cooler, but not sure why it would??
If your compressor is working , fans are working , assume all other usual A/C parts are all good . the hot water valve might be the issue if it’s always blowing Hot air . The valve is at “always Open” status , when the temp at control panel adjusted to lower than the cabin temp ( there’s temp sensor for cabin area measuring the temp) then the signal is sent to the valve to close it . It’s also possible that ur temp sensor is not working sending wrong data to the a/c ecu .
 

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1998 Lamborghini Diablo SV
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Discussion Starter #11
If your compressor is working , fans are working , assume all other usual A/C parts are all good . the hot water valve might be the issue if it’s always blowing Hot air . The valve is at “always Open” status , when the temp at control panel adjusted to lower than the cabin temp ( there’s temp sensor for cabin area measuring the temp) then the signal is sent to the valve to close it . It’s also possible that ur temp sensor is not working sending wrong data to the a/c ecu .
It's not blowing 'hot' air. Just not cold. It's cool-ish. Def not heater temp. Drove it prob 100 miles today. Outside a nice 80 degrees, but inside was god awful. Having the windows down was the only way I didn't suffocate. Going to see if it needs a simple recharge. Although this was done last summer, so if it's already out of refrigerant, then there must be a leak somewhere.
 

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It's not blowing 'hot' air. Just not cold. It's cool-ish. Def not heater temp. Drove it prob 100 miles today. Outside a nice 80 degrees, but inside was god awful. Having the windows down was the only way I didn't suffocate. Going to see if it needs a simple recharge. Although this was done last summer, so if it's already out of refrigerant, then there must be a leak somewhere.
Good then this is a much simpler issue to resolve .
 

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Any shop with an A/C gauge set should be able to test the system. The low side service port is in the driver's side rear wheel well. To access the high side port the rear panel (above muffler) needs to be removed. I recommend you remove it yourself before heading to the shop. Have the shop check to see if the system already has a leak detecting dye. If not, ask for it to be added. I don't recommend just adding refrigerant without knowing of what the problem is. Too much refrigerant can cause premature failure of other parts of the system.
 

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Any shop with an A/C gauge set should be able to test the system. The low side service port is in the driver's side rear wheel well. To access the high side port the rear panel (above muffler) needs to be removed. I recommend you remove it yourself before heading to the shop. Have the shop check to see if the system already has a leak detecting dye. If not, ask for it to be added. I don't recommend just adding refrigerant without knowing of what the problem is. Too much refrigerant can cause premature failure of other parts of the system.
A good shop doesn’t just fill your AC with freon. They will evac the residual freon and then fill it with freon under vacuum pressure.
 

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Discussion Starter #16
Update. Car had no refrigerant. Was just filled and checked in June of last year, so I assume there's a leak somewhere. The compressor is confirmed to work but it's not blowing cold air after the refill, so there's an electrical issue somewhere. Where do I start?
 

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Update. Car had no refrigerant. Was just filled and checked in June of last year, so I assume there's a leak somewhere. The compressor is confirmed to work but it's not blowing cold air after the refill, so there's an electrical issue somewhere. Where do I start?
So, I’m not too sure about Lambos... but I’ll say this...

a couple years ago, my suv wasn’t blowing AC. I checked the fuses, relays. They were fine. I the crawled under the vehicle and validated that the AC clutch was engaging when I turned on the AC. It did. So there were effectively 2 things to figure out. Did my system have a leak? Or was I out of AC?
I proceeded to purchase a $30 AC DIY canister from autozone. I put the AC into the low port valve. Still no blowing AC.

could still be a leak. I took the vehicle to a garage and they said it held pressure.

I told them I tried adding AC into the system. They said sometimes when the system gets too low of AC, the process of putting AC into the system won’t work via the low port alone. One has to add the freon once the system is purged of the old freon AND under vacuum.

I paid the $300 and they added the freon and it has worked ever since.

good luck
 

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1998 Lamborghini Diablo SV
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Discussion Starter #18
So, I’m not too sure about Lambos... but I’ll say this...

a couple years ago, my suv wasn’t blowing AC. I checked the fuses, relays. They were fine. I the crawled under the vehicle and validated that the AC clutch was engaging when I turned on the AC. It did. So there were effectively 2 things to figure out. Did my system have a leak? Or was I out of AC?
I proceeded to purchase a $30 AC DIY canister from autozone. I put the AC into the low port valve. Still no blowing AC.

could still be a leak. I took the vehicle to a garage and they said it held pressure.

I told them I tried adding AC into the system. They said sometimes when the system gets too low of AC, the process of putting AC into the system won’t work via the low port alone. One has to add the freon once the system is purged of the old freon AND under vacuum.

I paid the $300 and they added the freon and it has worked ever since.

good luck
Thanks. Seems my AC is working a lot better at the moment after the system was evacuated and recharged. Similar scenario may indeed be what happened. I picked up my car from the shop and immediately turned on the AC.....Vents seemed to be blowing considerably colder than before. Kept checking and indeed the air was colder through the vents. Possible the clutch may have seized and freed up once they ran power through it. Ambient temps were only around 70, so it's not entirely clear if the AC is doing a better job. The true test will be when it gets into the 90's with 80% humidity.
 

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If its any consolation one of my older cars has a leak that that takes about 2 years each time. I've tried tracing it down to anything, but its just too slow a leak to find when putting pressure on the system. Its just part of regular maintenance to refill right now.
 

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If its any consolation one of my older cars has a leak that that takes about 2 years each time. I've tried tracing it down to anything, but its just too slow a leak to find when putting pressure on the system. Its just part of regular maintenance to refill right now.
Might not apply to your vehicle, but It’s my understanding that AC system remains fairly good if the car is driven often. If it’s a car that only gets driven during the Summers, then the AC will tend to weaken if the car isn’t used often enough. Use it or loose it.
 
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