D3 Air con trouble

**Bowyang** · 8th January 2017, 12:54 PM

I have a strange fault in the air con of my 2005 TDV6. Sometimes it works perfectly and is quite cold, other times it is just cool, and yet at other times it can be ambient. The air temp can go through all three temperatures in 10 minutes. Other times it stays cold as it is set.I have had the gas topped up and the only fault showing is the cooling fan is running fast. It engages very shortly after engine start - even from cold. Any ideas please.

**LandyAndy** · 8th January 2017, 01:15 PM

My Bro is having the same issue on his D4.
Diagnosed as a faulty valve on the pump.Has been advised to replace the pump as a complete unit.
Being the tight arse he is he is trying to locate a new valve.
Andrew

**ytt105** · 8th January 2017, 01:36 PM

I think its called the TX valve.

What happens is the evaporator actually freezes and you cant get any air flow over it. Turn the air con off of five minutes and it will defrost and then the air will flow over the cold evaporator.
Mine does it once every blue moon, I think it happens when the outside temp goes up very quickly.

Regards
Trev

**LandyAndy** · 8th January 2017, 01:46 PM

Originally Posted by ytt105

I think its called the TX valve.

What happens is the evaporator actually freezes and you cant get any air flow over it. Turn the air con off of five minutes and it will defrost and then the air will flow over the cold evaporator.
Mine does it once every blue moon, I think it happens when the outside temp goes up very quickly.

Regards
Trev

In my Bros case the aircon takes along time to cool,yet sometimes its OK.No freezing of the evaporator as its still cooling.
His gas and pressures are good.
Andrew

**scarry** · 8th January 2017, 04:15 PM

The valve in the pump(compresser) is a completely different part to a TX valve.

Google is your friend,it will save me explaining the difference.

In short,

The compressors are unloaded,and loaded as needed,with a valve,which is probably the valve Andy is talking about.This is usually the issue in the D3/4.New compresser needed,expensive☹️(what item isn't in these vehicles?)

The TX valve is the main expansion device in the system.

There can also be many reasons why an evap freezes over,not just a fault with the TX valve.

**Bowyang** · 8th January 2017, 04:50 PM

The compressor cycles on and off as it always has. Would it necessarily do that with a crook valve?

**LandyAndy** · 8th January 2017, 06:50 PM

Originally Posted by Bowyang

The compressor cycles on and off as it always has. Would it necessarily do that with a crook valve?

My Brothers also cycles on and off as it would in the past.
Andrew

**scarry** · 8th January 2017, 07:41 PM

As far as i know the compresser is permanently engaged,variable displacement.(unless i am wrong)

Same as all modern AC systems,even our crapota vans are the same design.

So if it is cutting in and out,something else may be wrong

**LandyAndy** · 8th January 2017, 07:44 PM

Paul,I though the same.My Bro says the clutch on the front starts/stops like a normal AC pump.His is an early 3.0 D4.
Andrew

**BobD** · 9th January 2017, 10:49 PM

Originally Posted by LandyAndy

Paul,I though the same.My Bro says the clutch on the front starts/stops like a normal AC pump.His is an early 3.0 D4.
Andrew

My early (2009 build) D4 had the same problem. The compressor is variable displacement and when they wear the pressure to operate the valve which controls the variable displacement is too slow to build up pressure. both the valve and the compressor will be worn to cause this.

They don't cycle. The clutch is to stop the belt breaking if the compressor jams from what I have read.

I would highly recommend a new compressor. If you look up all the problems with VDC air cons (Land Rover, VW products and others) you will see that the compressor usually fails not too long after it starts playing up, even with a new valve.

On the 3.0l D4 the compressor is virtually inaccessible, whether to change the faulty valve which is in the compressor or the compressor itself. It took 2 full days to replace mine through a tiny hole underneath the car in front of the left front wheel. You can barely get your hand through the small opening to work on it but they did manage to change mine and it is now all fixed. I won't tell you the cost though! Kevin did mine, or at least the air con guy they use did it.

I requested a new compressor to fix my issues after it took ten minutes to start cooling on the way home from Rovertech on a 40 degree day after just spending significant money getting it regassed and the air con guy saying it was working perfectly.

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