ChrisG123

Some time ago the climate control started to flash on and off while on a trip. The flashes were about a second apart, none of the buttons would respond, the fan was off and I could hear a solenoid clicking behind the dash (in step with the flashing). When I got back home, I started to disconnect various sensors, solenoids etc to see whether one of them might be shorted out. I found that the flashing would stop when the refrigerant low pressure switch (F73) was disconnected. That way everything except the aircon worked. After a few days I plugged the low pressure switch back in and everything has been working well for six months until I got a VAG COM last week and cleared the fault codes yesterday. While I was clearing the fault codes, the climate control started flashing again and the connection to VAG COM was lost. I had to disconnect the low pressure switch before VAG COM could re-connect & the flashing would stop.

I have managed to do the following in VAG COM by starting the car without the low pressure switch connected and connecting the low pressure switch only once VAG COM has opened the HVAC:

1. Reading out the fault codes
2. Doing a basic setting
3. Running a self test (everything including the aircon works)

Now I'm back to driving the car with the low pressure switch disconnected, only problem is that it now starts to flash after about 5 min of driving. After switching the ignition off & on it's good for another 5 mins.

Any ideas? Thanks in advance.

Here is the list of current faults:

Saturday,27,October,2007,17:50:45:37730
VAG-COM Version: Release 704.1

Address 08: Auto HVAC
Control Module Part Number: 4A0 820 043 B
Component and/or Version: Klima-Vollautomat D05
Software Coding: 00061
Work Shop Code: WSC 06343
8 Faults Found:

00799 - Coolant Temperature Sensor (G110)
30-10 - Open or Short to Plus - Intermittent
00601 - Potentiometer On Positioning Motor for Central Flap (G112)
09-00 - Adaptation Limit Surpassed
00604 - Potentiometer Positioning Motor for Air Flow Flap (G113)
30-10 - Open or Short to Plus - Intermittent
00604 - Potentiometer Positioning Motor for Air Flow Flap (G113)
09-00 - Adaptation Limit Surpassed
00532 - Supply Voltage B+
07-00 - Signal too Low
00532 - Supply Voltage B+
07-10 - Signal too Low - Intermittent
00802 - A/C Refrigerant Low Pressure Switch (F73)
30-00 - Open or Short to Plus
00802 - A/C Refrigerant Low Pressure Switch (F73)
30-10 - Open or Short to Plus - Intermittent

The faults related to G110, G113 can be ignored as my car does not have these components. The pot on G112 is bad, but I don't think that this is causing the problem. The remaining codes are because of the unplugged low pressure switch.

DaveInSaltLake

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ChrisG123

Thanks for the info. I changed the wiring as described, but the flashing is still there. It seems like this technical bulletin applies to 1995 models. Mine is a 1993 2.8 right hand drive (I'm in South Africa) so the fuse and central electric panel are on the right.

Any other ideas?

ChrisG123

Problem solved by replacing control / display unit