Air Conditioning Stopped Working - Need Help

[Smokinram]

Hello,

The AC worked perfect last summer on my 2014 S4 and its finally getting warm here in Pennsylvania so I tried it over the weekend and nothing. So I figured maybe the system leaked down, but the system is holding pressure and is full of refrigerant. I changed the pressure switch on the condenser and no change. Does anyone have any ideas? I have VCDS VAG-COM. Is there a way to force on the AC compressor to see if its the compressor or something else causing the issue?
Thank you

[Audibot]

You should use VCDS to monitor the refrigerant pressure sensor (G65 I think) and it should tell you the pressure of the system. I don't recall the measuring blocks but it's in HVAC. You should also check the fault codes to see what it says. Usually a refrigerant low pressure code is triggered. Obviously if you are low, you have a leak (probably condenser) and should have the offending component(s) checked out and replaced. And then evacuate and refill the system.

VCDS can't force it on and you should not anyway as to not risk damage.

If the pressure is too low when you put the a/c on, it will not kick on. At rest (no a/c on) it should be somewhere between ~5.5 and ~6.5 bar (~80-95) psig. When you turn the a/c on, the low side should go down to ~3 bars.

If nothing changes, it's likely your compressor is toast. In which case you will need to replace it and and should replace the orifice valve and accumulator, and flush out all the lines and condenser from metal fragments.

[Smokinram]

You should use VCDS to monitor the refrigerant pressure sensor (G65 I think) and it should tell you the pressure of the system. I don't recall the measuring blocks but it's in HVAC. You should also check the fault codes to see what it says. Usually a refrigerant low pressure code is triggered. Obviously if you are low, you have a leak (probably condenser) and should have the offending component(s) checked out and replaced. And then evacuate and refill the system.

VCDS can't force it on and you should not anyway as to not risk damage.

If the pressure is too low when you put the a/c on, it will not kick on. At rest (no a/c on) it should be somewhere between ~5.5 and ~6.5 bar (~80-95) psig. When you turn the a/c on, the low side should go down to ~3 bars.

If nothing changes, it's likely your compressor is toast. In which case you will need to replace it and and should replace the orifice valve and accumulator, and flush out all the lines and condenser from metal fragments.

Thanks for the quick reply. I did use the VAG COM and went into HVAC and tried to find the measuring blocks for the pressures and could not find anything. Also checked codes and there are no codes present. I will hook my gauges back up and check the pressures and see. maybe it is a little low and just causing it to not activate. Just strange though, a leak usually drops out all pressure, but initial testing, it showed good pressure in the system with my manual gauges.

[Audibot]

Thanks for the quick reply. I did use the VAG COM and went into HVAC and tried to find the measuring blocks for the pressures and could not find anything. Also checked codes and there are no codes present. I will hook my gauges back up and check the pressures and see. maybe it is a little low and just causing it to not activate. Just strange though, a leak usually drops out all pressure, but initial testing, it showed good pressure in the system with my manual gauges.

It should be one of the first measuring block groups. "Refrigerant Circuit Pressure (G65)". Or you can do the Advanced Measuring blocks and search for it. It should give you a reading.

Dumb question: Did you plug it back in when you replaced it?

[Smokinram]

It should be one of the first measuring block groups. "Refrigerant Circuit Pressure (G65)". Or you can do the Advanced Measuring blocks and search for it. It should give you a reading.

Dumb question: Did you plug it back in when you replaced it?

Haha yes I did plug the new pressure sensor back in. I will check again with VAG COM and see what I can figure out. Just can't imagine a compressor would go bad over the winter for no reason.

[Audibot]

My B7's compressor just went randomly one day. It happens.

[audigsr]

Happened to me last summer, was thinking it was the pressure sensor as well. Took it to a indy shop and my refrigerant levels were super low somehow. They put dye in and could not locate a leak, but since refilling its been blowing ice code. At least I should know where its leaking next time it happens.

[Smokinram]

You should use VCDS to monitor the refrigerant pressure sensor (G65 I think) and it should tell you the pressure of the system. I don't recall the measuring blocks but it's in HVAC. You should also check the fault codes to see what it says. Usually a refrigerant low pressure code is triggered. Obviously if you are low, you have a leak (probably condenser) and should have the offending component(s) checked out and replaced. And then evacuate and refill the system.

VCDS can't force it on and you should not anyway as to not risk damage.

If the pressure is too low when you put the a/c on, it will not kick on. At rest (no a/c on) it should be somewhere between ~5.5 and ~6.5 bar (~80-95) psig. When you turn the a/c on, the low side should go down to ~3 bars.

If nothing changes, it's likely your compressor is toast. In which case you will need to replace it and and should replace the orifice valve and accumulator, and flush out all the lines and condenser from metal fragments.

Finally got around to checking with my VAGCOM and here is what I see:

Car running, AC switch off,
AC regulating valve N280 - 0.000 A
Refrigerant Pressure G395 - 6.2 Bar

Car running, AC switch on,
AC regulating valve N280 - 0.600 A
Refrigerant Pressure G395 - 6.2 Bar

I am assuming this is telling me my refrigerant pressure is good, pressure switch is also good, and compressor is bad. Am I correct?

Thank You

[Audibot]

That seems like the same symptoms I had when my a/c compressor killed itself.