Air Conditioner Compressor Not Working

[zookie]

2013 S4 Air conditioner compressor no longer comes on. I've done some googling and read some cases of a pressure switch causing the compressor to not come on. Are there are images or documents out there than anyone is aware of that has the location of these and the part numbers? I've seen them in different places on older models but not on the B8/85 S4.

Figured I'd start by swapping pressure sensors myself and just hope that it isn't the actual compressor. Unless there's a DIY way to test the compressor?

Fortunately it's the right time of year for the A/C to not function but when set to auto, the fan essentially blows all the time even when the heater is doing the work to keep the cabin warm.

Haven't pulled VCDS but will tonight.

[zookie]

Never had to bump a thread here before. Anyone know what I'm talking about? Fortunately it's winter so it hasn't been an issue but spring will be here quick!

[Loe]

pressure sensors are housed within the compressor, it's not a serviceable item on the B8.5's

In VCDS, you should be able to log the output of the compressor under the Auto-HVAC setting. If your compressor is seeing a PWM signal, voltage/amps, but your high side pressures are low, then your compressor does not work. Another way is to measure your low/high side and compare pressure readings; if the compressor kicks on, then the high side should jump closer to the 200psi (depending on ambient temps obviously), but if it remains the exact same or around the low side readings, then something is wrong with the compressor

[chaos2984]

pressure sensors are housed within the compressor, it's not a serviceable item on the B8.5's

In VCDS, you should be able to log the output of the compressor under the Auto-HVAC setting. If your compressor is seeing a PWM signal, voltage/amps, but your high side pressures are low, then your compressor does not work. Another way is to measure your low/high side and compare pressure readings; if the compressor kicks on, then the high side should jump closer to the 200psi (depending on ambient temps obviously), but if it remains the exact same or around the low side readings, then something is wrong with the compressor

I will expand on this. R134 A should read the same pressure as ambient outside temp +- a few when the car is off or A/C not running. if you pressures are way lower than ambient temp then your low on freon and you have a leak. Thats if you haven't gone though a heatsoak on the engine. Also If you can get a friend with R134A manifold gauges it will take about 10 min to check to see if the system is working correctly. Also if you have vag com you can hook up and check for faults in the ECM or HVAC system related to the compressor and monitor temps.

[zookie]

Just to close off this thread, thank you for the advice. Issue was pressure sensor. Replaced and all good!

[Jezza]

How did you replace the pressure sensor?

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[zookie]

Audi did it under CPO because I got busy with work so I had to just get it done. Not sure if I won or lost with the CPO deductible. Sorry not more help.

[steampunkjunker]

Not true. The AC Pressure Sensor is serviceable and can be replaced without loosing refrigerant.

https://www.ecstuning.com/b-genuine-...ch/4h0959126b/

pressure sensors are housed within the compressor, it's not a serviceable item on the B8.5's

In VCDS, you should be able to log the output of the compressor under the Auto-HVAC setting. If your compressor is seeing a PWM signal, voltage/amps, but your high side pressures are low, then your compressor does not work. Another way is to measure your low/high side and compare pressure readings; if the compressor kicks on, then the high side should jump closer to the 200psi (depending on ambient temps obviously), but if it remains the exact same or around the low side readings, then something is wrong with the compressor

Sent from my iPad using Audizine