2.5 tdi air con problems

Problems with the air con on my 03 2.5tdi quattro. Fault codes read as follows ;
V158 left side motor temperature valve blocked or no voltage
V159 Right side motor temperature valve blocked or no voltage
A/C compressor appears to be running as the feed pipe gets cold to evaporator. Despite the codes above both drivers and passenger temp control flap motors are moving full cycle when the temp is increased or decreased on the control head. The system is full of gas and there appears to be no other faults. No matter what the system will always only blow ambient air temperature. I should be grateful for advice on what the fault codes mean and how to get this problem resolved.

sounds like the motors are duff

i thought so too until I removed the lower dash panels and you can see both motors opening and closing fully when increasing and decreasing temperature on the control head. Even with the motors removed and moving the flaps to full cold manually the system still blows ambient air temperature. I'm wondering if there are any hidden motors or something else stopping the cold from the air con system being channeled through to the cabin. Any suggestions ?

did you check the recirc flap motor at the side of the dash?

Yep it is ok. Opening and closing on demand as expected. Cold pipe from compressor to cabin isnt forming ice though , just condensation. Could it be that the compressor is duff and if so can it be tested. Alternatively maybe the guy checking the gas is just an idiot and is telling me lies that the system is full.

Finally found an air con specialist who knew what he was talking about. Although I reckoned the system was working because the pipe was cold he said straight away that it was the wrong pipe that was cold. Apparently only the thicker pipe should be stone cold and the thinner one should be slightly warm. It was the opposite on mine. He diagnosed a blocked reed plate which is a plastic gauze filter / valve which can be accessed by unscrewing the narrow pipe just next to the filler nozzles. System was degassed and the reed plate removed and replaced with new and refilled with gas. Hey presto all is now working a treat. A lot of wasted time and effort by going to a turnip in the first place. My advice , steer clear of back street garages and go to a specialist for anything , even a simple regas.

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Originally Posted by abyrne153

Finally found an air con specialist who knew what he was talking about. Although I reckoned the system was working because the pipe was cold he said straight away that it was the wrong pipe that was cold. Apparently only the thicker pipe should be stone cold and the thinner one should be slightly warm. It was the opposite on mine. He diagnosed a blocked reed plate which is a plastic gauze filter / valve which can be accessed by unscrewing the narrow pipe just next to the filler nozzles. System was degassed and the reed plate removed and replaced with new and refilled with gas. Hey presto all is now working a treat. A lot of wasted time and effort by going to a turnip in the first place. My advice , steer clear of back street garages and go to a specialist for anything , even a simple regas.

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Sound's like what mine is doing little pipe leading into the pollen filter as ice on it and the other one does not but mine is a passat.
Not to be nosiey but ut was it it pricey to have done.

£60 all in cash. It may be the same problem with yours as the bigger pipe should be the colder one. The reed plate is a little plastic gauze like filter about 3 or 4 inches long and by the look of it probably only costs a couple of quid. The system need vacuumed out though before changing it. He simply split the pipe at the 2 nuts beside the refill valved and pulled out the reed valve with a pair of sharp nosed pliers. Fitting was the reverse and the whole thing took less than 45 minutes start to finish. Be careful to go to someone who knows what they are doing as I wasted an awful lot of time by listening to the first idiot.

Hi All

I have just bought an A4 Avant 2.5 TDI V6 and i have the same fault where did you did it fixed, did you go to the dealers as i have had my car re-gassed and pressure checked twice only to be told that i have no fault on my air con system.

Got it fixed eventually at a vehicle air con specialist (Bosch equipment). I didnt go to an Audi dealer.