Random air con

[shack]

Hi guys,

Just heading interstate and the a/c in the front of our d3 is playing up, I think it might have been for several weeks, but of course now it's more of an issue!

The front vents put out cold air but not for very long, in fact we were having to turn it off and back on every couple of minutes to get any relief.

I then told the kids they had to turn on the a/c for their seats and set the temperature all the way down, since they did that the front has been blowing cold for about 20 minutes.

Any thoughts as to what the problem might be?

Cheers
James

[LRD414]

Search is your friend. Have a read of these threads ....

D4 A/C Compressor issue (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/268239-d4-c-compressor-issue.html)

D3 Air con trouble (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/244741-d3-air-con-trouble.html)

And a detailed explanation in this one, eg post 28

2013 D4 Air Conditioner Issue (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/268088-2013-d4-air-conditioner-issue-3.html)

Regards,
Scott

[jwb]

Got the same problem - started last summer. Booked in for couple of weeks - going to request they replace the compressor under my extended warranty.
Also to fix driver's door random not working from outside.

[DiscoJeffster]

Firstly have you ever regassed it? That’s the first port of call.
After that, the compressor displacement valve can fail, and is cheaper to change than an entire compressor. Simpler is simply a new compressor, but lots of money.

Beyond that you’re into rare issue territory

[jwb]

Re-gassed last summer when the problem surfaced. It was down a little.
Didn't really do much to the randomness of the system coming on.
From reading the threads here it's likely the valve, I'll ask the LR service if they do only that.

[DiscoJeffster]

Re-gassed last summer when the problem surfaced. It was down a little.
Didn't really do much to the randomness of the system coming on.
From reading the threads here it's likely the valve, I'll ask the LR service if they do only that.

Unlikely. They’ll want to swap the compressor. Go to an AC place and get them to do it. Process is buy valve (them or you), degas, undo circlip holding valve, regas with nitrogen until valve fires out under pressure, replace valve, vacuum and regas.

[shack]

Firstly have you ever regassed it? That’s the first port of call.
After that, the compressor displacement valve can fail, and is cheaper to change than an entire compressor. Simpler is simply a new compressor, but lots of money.

Beyond that you’re into rare issue territoryYeah I checked the gas myself last week, all good, I think I did read those threads but couldn't see how it applied to our car, I'll have another look though, thanks.

Cheers
James

[theelms66]

Yeah I checked the gas myself last week, all good, I think I did read those threads but couldn't see how it applied to our car, I'll have another look though, thanks.

Cheers
JamesHow did you check the gas?
The accurate way is to weigh the gas . Which means degas and regas yes?

[theelms66]

My l322 was cooling to start with then the more it ran the less it cooled. Pressures were all over the place . Degas and regas with correct weight gas and now its great.

[shack]

How did you check the gas?
The accurate way is to weigh the gas . Which means degas and regas yes?Just put the gauges on, seemed to be running ok to me

[DiscoJeffster]

Just put the gauges on, seemed to be running ok to me

Feedback is the gauges aren’t a good indicator. Well worth getting it dumped, weighed and refilled.

[BradC]

Feedback is the gauges aren’t a good indicator. Well worth getting it dumped, weighed and refilled.

Gauges are a decent indicator of "is it running or not". ie. If the displacement valve is stuck you'll have a low high side and high low side (ie it's not moving much gas). You won't get a reliable indicator of charge level though.

I've never played with a dual evaporator unit, but it would be worth checking the pressures when it's working well (ie the rear is running flat out) vs not working well (or at all).
If the symptoms are reproducible it should be a doddle.

Given the described symptoms, have a think about this as a scenario.

A sensor is keeping the displacement valve wide open. With the front evap only the thing gets so cold it ices up. Requires a manual off/on cycle to defrost it. With the rear evap on the extra demand is enough to keep the suction temp above freezing and everything is peachy.

If you can manually turn it off then it won't be a physically jammed valve. Cabin temp sensor telling the controller it's always too hot? Do you have a scan tool?

If the evap is icing you'll see that on the gauges anyway.

[shack]

All fixed now,

Was just a partially blocked pollen filter, I'm pretty pleased to say the least...

[jwb]

Mine was fixed last week - new compressor.
Regas last summer and pollen filter didn't help. Compressor fault diagnosed I don't know what exactly.
Happily covered by my extended warranty/insurance.

[DiscoJeffster]

Mine was fixed last week - new compressor.
Regas last summer and pollen filter didn't help. Compressor fault diagnosed I don't know what exactly.
Happily covered by my extended warranty/insurance.

Generally it a $60 displacement valve in the compressor that fails but a dealer won’t change the valve as it’s not a spare part for them. AC places will sometimes if they can’t get the customer to spring for a complete compressor. I had my valve changed when I had the body off as they had to degas anyhow and access was easier. Definitely much quicker to start cooling than it was. Sometimes it took ten minutes before it would work.

As a side note, VW compressors eat themselves regularly and spit crap through the system so their repair costs are far higher. Compressor, condenser, etc all have to be replaced else the crud will contaminate and destroy the new compressor.