AC and engine cooling fan not working

[Dardani2000]

Anyone knows where this sensor is located
DTC B10AE21 (High-pressure sensor Lower limit not reach).
I can't seem to find any information about it

[oesman]

The high pressure sensor is found on the right side, around the middle, of the condenser coil. I've attached a picture, it's #7 in the picture.

Are you sure the sensor is bad? The code doesn't necessarily mean a bad sensor. DTC indicates the sensor is tripped due to not meeting minimal pressure on the high side. If you have a scan tool like VCDS try to see if you can read the sensor and see if it's showing any pressure. If the sensor is giving data then it's probably not bad. If that's the case then you have a leak somewhere which will require tracing with a sniffer tool and/or uv reactive dye.

If you're not familiar it's best to have someone else perform the work at this point. Don't mess with those AutoZone refill kits, they're garbage. If you do wanna try your luck at just topping it up and seeing how long it lasts (it went somewhere) at least get a decent set of gauges from amazon and a few cans of refrigerant with dye to go with it, that way you can properly fill the system to capacity and not over/under like with the AutoZone junk. VW does not approve the use of stop leak chemicals, nor have I found those useful myself. Capacities are 590 grams for R134a and 525 grams for R1234yf, depending on which your car has (early 2018 MY had R1234yf).

You can also throw some gauges on and see if the pressure is good with the AC running, which would point to bad sensor. If you do find that it's the sensor, you need to take the top cover above the front fascia off, not sure if the fascia has to come off or not, but on RS grille I believe you can keep the fascia on for sure. It does say to replace the o-ring and coat it with refrigerant oil. Also if refrigerant flows for more than a second when you loosen the sensor, tighten it back up, it means the upstream check valve is broken and will need to be replaced as it's going to dump out your refrigerant.

[Dardani2000]

Thank you for helpful information.
AC only stays on for couple seconds when I start the car and than it turns off, and I can't turn it on anymore while the car is running. But with engine off and ignition on AC will stay on.

[oesman]

With engine off the compressor isn't running so it's just blowing air around, it's not checking for pressure readings at that time, which is why the system stays on. Once your engine is running it will be checking high and low side pressures to make sure you have adequate refrigerant and reduce potential for damage. So either you are low on refrigerant because of a leak somewhere or the sensor is bad and the computer just thinks there's a leak. Did it get progressively worse at all? Small leaks may cause a progressive decline in performance, big leaks obviously not so much. You can pay pretty much any shop to throw some gauges on and get you some readings, at least rule out sensor vs. leak. Then you can decide if you're gonna try to diy this or go to a indie VAG mechanic or the dealer.

[Dardani2000]

I'm not even sure when my AC stopped working. There was no signs of it going bad

[Smac770]

If the radiator fans are not working, then the refrigerant is not going to drop in temp and it'll over pressure and shut down.

You need to look at the measuring values for the radiator fan duty cycle and confirm that the ECM is directing the fans to be on. Then look at the fans and see if they are doing as directed.

Were to assume this is the CWGD engine? Then make sure the S42 fuse at the engine compartment terminal 30 distribution block (where the + jump start post is) is ok. (I assume your fuse config in that panel is the single S42 fuse, 70A, as I don't believe any US A4 is towing prepped (1D8)).

If you have no errors from 01-engine and the fuse is ok and the ECM measuring value says it's saying "spin fan, spin", then one has to assume something is broken about the fan motor or fan motor controller.

[oesman]

If the radiator fans are not working, then the refrigerant is not going to drop in temp and it'll over pressure and shut down.

True, but he's getting a code for not meeting minimal pressure and the AC shuts off just after he starts the car. So it's likely he's got a leak somewhere, hopefully not the evap coil though. He hasn't given much info on the fans though.

[Dardani2000]

Quick update...
I had Audi dealer look at it and they couldn't find any leaks after vacuum leak test. It was really low at refrigerant they recharged the system and added dye still they didn't locate any leaks. So $309 later I got ice-cold AC and still don't know where my old AC went.

[oesman]

Quick update...
I had Audi dealer look at it and they couldn't find any leaks after vacuum leak test. It was really low at refrigerant they recharged the system and added dye still they didn't locate any leaks. So $309 later I got ice-cold AC and still don't know where my old AC went.

:( hopefully they find the leak with the dye, but makes it sound like the evap coil since it's buried in the dashboard you can't really check it with a sniffer (it has to be right up close to the leak source). If it was the condenser coil, compressor or lines I suspect they would have found it. Evap coils can have pretty small leaks plus they expand/contract frequently, which is also why they fail a lot.