Would a bad compressor throw codes...i would think so

[ju1ce]

AC was blowing warm, 64k b8.5.

To me, it seemed like the compressor was turning on, I ran vag and no codes. So, i figured a leak, and lost all 134.

An independent shop says it needs a new compressor. $1,600 (w/ non oem part). But I would think that would throw codes.

[Audibot]

Could be broken internally. So the car is telling the compressor to kick on and the compressor is trying but something is broken so it's not actually working. Likely to do with actuating the swash plate.

This is what happened to my B7's compressor.

$1600 is a ridiculous price.

[Smac770]

You'd need to monitor live data and see what's going on. Measuring blocks in address 0x08, climate control. Look for the N280 activation current and the G395 refrigerant pressure. The N280 current should go to .65A on turn on and work it's way down from there as less pressurization is needed. The G395 pressure should have a value before and an increased value after turn on. If there's no an operational issue with one of those two mechanisms, then the car otherwise knows nothing about what's going on with the compressor.

I would think $500 is the most I'd pay for an OEM or third-party replacement compressor. Even a brand new OE unit is only $800, https://www.genuineaudiparts.com/oem...sor-8t0260805n. But I'd get a used one before bothering with that kind of price, https://wolfautoparts.com/ac-compres...e-ps24928.html

[vincent_nguyen2]

I know if you are under the lower limit of refrigerant then when you press the AC button, it’ll light up like usual but immediately turn off. If you do a full VCDS scan, you’ll also see a code for being under the lower limit which would be the case if you had a leak I’m assuming

[ju1ce]

Good to know.in my case light stayed on and no codes. It seems the compressor may have been coming, but doing nothing. They replaced the compressor and dryer, 1600 parts and labor and all is good. Next time I'm picking up gages and doing my checks myself before sending it to the shop. For ref, audi wanted 2900 to replace the compressor.

[A4fuzz]

There's a pressure sensor in the hard line that can be seen and accessed through the grille. I just replaced mine after messing with erratic AC issues and its back to normal. There's some threads on here about it, that's how I figured it out. It's probably worth trying as it was a pretty cheap part on amazon.

[ju1ce]

Yeah my pressure sensor was replaced at 36k while fixing a Schrader valve leak. But my issue was consistent. No cold air at all.

[RPMtech147]

No codes is usually a pretty good indication it needs a compressor. If the wire to the compressor solenoid is disconnected/broken it throws a code. If the pressure sensor is faulty, it throws a code. If the pressure is too low (No refri) it throws a code. If the compressor has a mechanical failure the system has no way to know it it. It sees enough static pressure to not fault and all electronic signals are GTG.

You can buy an aftermarket compressor for around +/- $400. It literally takes 45 minutes to change, even doing it on your back. When I do them at work it takes me longer too evac/charge the system then it does to actually lift the car and swap the compressor out.

I'm sure that $1600 includes replacing the receiver/dryer though which may be a desiccant bag on the side of the condenser. Some years you can change the bag, others you have to replace the entire condenser.

[ju1ce]

No codes is usually a pretty good indication it needs a compressor. If the wire to the compressor solenoid is disconnected/broken it throws a code. If the pressure sensor is faulty, it throws a code. If the pressure is too low (No refri) it throws a code. If the compressor has a mechanical failure the system has no way to know it it. It sees enough static pressure to not fault and all electronic signals are GTG.

You can buy an aftermarket compressor for around +/- $400. It literally takes 45 minutes to change, even doing it on your back. When I do them at work it takes me longer too evac/charge the system then it does to actually lift the car and swap the compressor out.

I'm sure that $1600 includes replacing the receiver/dryer though which may be a desiccant bag on the side of the condenser. Some years you can change the bag, others you have to replace the entire condenser.

This is great info. Makes me feel better that is indeed what the issue was. Yes, fix included the dryer. Non oem.