Air Conditioning blowing warm air on 2009 A4 - anyone else had this happen yet?

B8 A4
#1

It was about 70 degrees on Saturday so I turned on the AC, but it just blew warm air.

Wondering if anyone has had this happen or has had similar codes…hoping it’s just a replacement of the sensor. Havent seen a DIY on that anywhere, so if you’ve seen one, please link it up.

Wednesday,20,April,2016,09:04:08:02319
VCDS Version: Release 14.10.0

            Address 08: Auto HVAC       Labels: Redir Fail!

Control Module Part Number: 8T1 820 043 AC HW: 8T1 820 043 AC
Component and/or Version: KLIMA 3 ZONEN H06 0140
Software Coding: 64002000
Work Shop Code: WSC 06335 000 00000
VCID: 72E1EA83ADA62EB169F-8027
3 Faults Found:

00256 - A/C Pressure/Temperature Sensor (G395)
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 7
Fault Frequency: 254
Reset counter: 159
Mileage: 133004 km
Time Indication: 0
Date: 2016.01.26
Time: 11:42:11

         Freeze Frame:
                Temperature: 19.0°C

00457 - Control Module for Network (J519)
013 - Check DTC Memory - Intermittent
Freeze Frame:
Fault Status: 00101101
Fault Priority: 6
Fault Frequency: 254
Reset counter: 159
Mileage: 133004 km
Time Indication: 0
Date: 2016.01.26
Time: 11:42:10

00256 - A/C Pressure/Temperature Sensor (G395)
001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 2
Fault Frequency: 254
Reset counter: 146
Mileage: 137565 km
Time Indication: 0
Date: 2016.04.15
Time: 22:25:51

         Freeze Frame:
                Temperature: 17.0°C
                Temperature: 82.0°C
                Load: 0.0 %
                Absolute Pres.: 31.8 bar
                RPM: 0 /min
                Speed: 0.0 km/h
                Current: 0.000 A
                Temperature: 17.0°C
#2

The AC high pressure switch has been revised for most of the B8s. I replaced a bunch when I still worked at the dealerships. One of the easiest repairs too. Just take off the big black cover between the grill and radiator then the high pressure switch is on top of the AC condenser by the driver’s side headlight.

#3

The part number should be: 4H0959126A

https://www.ecstuning.com/Audi-B8_A4-Quattro-2.0T/Climate_Control/Air_Conditioning/Electrical/ES2610055/

#4

cool. Should I try to do that and see if that solves it without needing a re-gas?

I have a warranty but I’m not 100% sure if this is covered. If there is corrosion causing this, it’s not. If the sensor failed, it is (including a re-gas)

#5

The sensor should be covered because they fail. There likely is an updated part. The AC condenser has a valve in the nipple that the high pressure switch screws on so it stops most of the refrigerant from leaking out. Only a small puff would leak out when removing the switch. Audi wouldn’t pay for a refrigerant drain/fill under warranty on basically any Audi for replacing the high pressure switch. It seriously is one of the easiest repairs ever and I would replace them in the parking lot with basic hands tools.