D4 Intermittent Air Con

[Celtoid]

Hi All,

I'm unsure how the D4 A/C works and whether or not any faults get registered in the CPU.

Over the last few months or so my A/C has been a bit slow to come on, from time to time. More often than not it's fine.

OAT makes no difference at all ... it can be 43 degrees and start cooling almost instantly or take up to 5 minutes. I don't mean cooling affect in the car, I mean temperature right at the vents.

It's usually first start of the day but yesterday it did it late afternoon.

It also seems very, very cold for the selected temperature, from time to time.

I know if I book it into LR, it will work flawlessly ... LOL!!!

Anybody else had this issue?

Cheers,

Kev.

[BobD]

Kev,

I had the same issue on my previous car, a VW Multivan. It only occured after they repaired the A/C under warranty when the compressor flexible drive broke and it would consistently take several minutes to start cooling. Annoying and the dealer told me there was nothing wrong! I gave up trying to get it fixed and it was still the same when I sold the car.

Interestingly, the VW had the same system with constantly on compressor and varying gas flow to suit the cooling required. Sounds to me like the variable flow valve (probably not the correct wording but you know what I mean) is sticking in both cases. Since yours is also too cold sometimes, that confirms even more that the valve is probably misbehaving.

Bob

[Graeme]

D4 3.0 compressors have an electro-magnetic clutch to engage/disengage the drive, unlike the D3 & D4 2.7 compressor.

[Celtoid]

D4 3.0 compressors have an electro-magnetic clutch to engage/disengage the drive, unlike the D3 & D4 2.7 compressor.

Thanks Graeme,

So I'm assuming if it's hot inside the car, a sensor 'tells' the system to enable the a/c system and the clutch is engaged? And then temperature control is achieved by a sensor 'telling' a valve to regulate the air coming into the car .... or does the clutch just keep engaging and disengaging as required to regulate the temp?

Either way then, I guess it's either a clutch or sensor(s) problem?

Shame it's intermittent ....

Cheers,

Kev.

[jonesy63]

Hi Kev,
The sensor is behind the grill to left hand side of steering wheel on the dash. As well as the clutch engaging, there is a stepper motor in the dash - which controls how much cool/hot air goes through to the cabin.

IIRC, there was a problem with these stepper motors in the D3 - where it made farting sounds! (Yes dear.. it was the car that time, not me! :D ) The repair was a dash-out job! :eek:

Could be a problem with the stepper, compressor clutch, or sensor...